We really need to stop obsessing over the clothes of women. Its like every YouTube video, every fatwa website has content crying over the dress of women.
Lets do a history lesson. The head covering was a part of the arab culture. It was worn BEFORE Islam arrived. Islam did not invent the hijab. It was already in existence worn by people of many faiths (or no faith). However, the head covering (referred to as khimar in the Quran) did not cover the front of a woman. It didn't cover her chest. The head covering would hand behind the woman. That is why Allah said for women to take their head covering (which is ALREADY being worn since its the CULTURE) and cover the exposed parts of the body. Allah never said for women to cover their heads, he just said to take it and cover the front, which was a commandment to the women in ARABIA (and surrounding countries).
And also, there are no sound hadiths on hijab. This is why even the most conservative of Salafis still use the Quran as their primary source of evidence to prove hijab (even though they are wrong).
The overall general idea is that women should dress modestly. Modesty varies by culture. In countries where burka is the only form of modesty, that culture will pass out when they see cultures where burkas are not the only form of modesty. Tight and revealing clothes is what's haraam in Islam. And keep in mind, most women wear clothes that they are comfortable in, in the same way men wear clothes that they feel comfortable in. Most women don't purposely show off their curves, they're just shaped like that, and we need to stop crying over this. The same goes for us men, we don't try and show off our body shapes. But the shape of our parts will almost always show (at least a little bit). You cannot avoid this. Body shapes will ALWAYS show no matter what the clothing is. Shapes will show if you wear jeans, shapes will show if you wear a burka.
Most Muslim girls living in the west do not wear hijab. If anything most of the ones that do are of Arab or Somali decent. Because its their culture. Most Muslim women here wear regular western clothes like everyone else, just like how most Muslim men do. And yes, western clothes can ALSO be modest. Please get bikinis, leggings, spaghetti straps OUT of your head, because that's not the only type of western clothing that exists.
I have said before, culture heavily influences our views on Islam. People who live in cultures where women wear burkas and are segregated from public life will automatically assume women are wearing immodest clothes if they go to places where wearing burkas is not the norm. They won't be able to see that women can still be modest WITHOUT wearing burkas and hijabs.
We need to stop sexualizing every inch of a woman's body. We need to stop thinking that women are sex objects who need to be covered because us men can't "control" ourselves. A woman's choice of clothing should not be determined on the basis of how men will react. If men wear clothing that they are comfortable in, why can't the same apply to women? A woman can be modest WITHOUT covering her hair, while wearing any type of clothing she wants to.
There are two Quran verses that talk about a woman's dress. Surah An Nur (24:3)1 and Surah Al Azhab (33:59). I'll show 24:31 with various translations:
"And tell the believing women to reduce [some] of their vision and guard their private parts and not expose their adornment except that which [necessarily] appears thereof and to wrap [a portion of] their headcovers over their chests and not expose their adornment except to their husbands, their fathers, their husbands' fathers, their sons, their husbands' sons, their brothers, their brothers' sons, their sisters' sons, their women, that which their right hands possess, or those male attendants having no physical desire, or children who are not yet aware of the private aspects of women. And let them not stamp their feet to make known what they conceal of their adornment. And turn to Allah in repentance, all of you, O believers, that you might succeed."
Mufti Taqi Usmani
And tell the believing women that they must lower their gazes and guard their private parts, and must not expose their adornment, except that which appears thereof, and must wrap their bosoms with their shawls, and must not expose their adornment, except to their husbands or their fathers or the fathers of their husbands, or to their sons or the sons of their husbands, or to their brothers or the sons of their brothers or the sons of their sisters, or to their women, or to those owned by their right hands, or male attendants having no (sexual) urge, or to the children who are not yet conscious of the shames of women. And let them not stamp their feet in a way that the adornment they conceal is known. And repent to Allah O believers, all of you, so that you may achieve success.
And tell believing women that they should lower their glances, guard their private parts, and not display their charms beyond what [it is acceptable] to reveal; they should let their headscarves fall to cover their necklines and not reveal their charms except to their husbands, their fathers, their husbands’ fathers, their sons, their husbands’ sons, their brothers, their brothers’ sons, their sisters’ sons, their womenfolk, their slaves, such men as attend them who have no sexual desire, or children who are not yet aware of women’s nakedness; they should not stamp their feet so as to draw attention to any hidden charms. Believers, all of you, turn to God so that you may prosper.
And say to the believing women that they should lower their gaze and guard their modesty; that they should not display their beauty and ornaments except what (must ordinarily) appear thereof; that they should draw their veils over their bosoms and not display their beauty except to their husbands, their fathers, their husband's fathers, their sons, their husbands' sons, their brothers or their brothers' sons, or their sisters' sons, or their women, or the slaves whom their right hands possess, or male servants free of physical needs, or small children who have no sense of the shame of sex; and that they should not strike their feet in order to draw attention to their hidden ornaments. And O ye Believers! turn ye all together towards Allah, that ye may attain Bliss.
And say to the believing women that they cast down their looks and guard their private parts and do not display their ornaments except what appears thereof, and let them wear their head-coverings over their bosoms, and not display their ornaments except to their husbands or their fathers, or the fathers of their husbands, or their sons, or the sons of their husbands, or their brothers, or their brothers' sons, or their sisters' sons, or their women, or those whom their right hands possess, or the male servants not having need (of women), or the children who have not attained knowledge of what is hidden of women; and let them not strike their feet so that what they hide of their ornaments may be known; and turn to Allah all of you, O believers! so that you may be successful.
And tell the believing women to lower their gaze and be modest, and to display of their adornment only that which is apparent, and to draw their veils over their bosoms, and not to reveal their adornment save to their own husbands or fathers or husbands' fathers, or their sons or their husbands' sons, or their brothers or their brothers' sons or sisters' sons, or their women, or their slaves, or male attendants who lack vigour, or children who know naught of women's nakedness. And let them not stamp their feet so as to reveal what they hide of their adornment. And turn unto Allah together, O believers, in order that ye may succeed.
And tell the believing women to lower their gaze (from looking at forbidden things), and protect their private parts (from illegal sexual acts, etc.) and not to show off their adornment except only that which is apparent (like palms of hands or one eye or both eyes for necessity to see the way, or outer dress like veil, gloves, head-cover, apron, etc.), and to draw their veils all over Juyubihinna (i.e. their bodies, faces, necks and bosoms, etc.) and not to reveal their adornment except to their husbands, their fathers, their husband's fathers, their sons, their husband's sons, their brothers or their brother's sons, or their sister's sons, or their (Muslim) women (i.e. their sisters in Islam), or the (female) slaves whom their right hands possess, or old male servants who lack vigour, or small children who have no sense of the shame of sex. And let them not stamp their feet so as to reveal what they hide of their adornment. And all of you beg Allah to forgive you all, O believers, that you may be successful.
And say to the female believers to cast down their be holdings, and preserve their private parts, and not display their adornment except such as is outward, and let them fix (Literally: strike) closely their veils over their bosoms, and not display their adornment except to their husbands, or their fathers, or their husbands' fathers, or their sons, or their husbands' sons, or their brothers, or their brothers's sons, or their sisters' sons, or their women, or what their right hands possess, or (male) followers, men without desire (Literally: without being endowed with "sexual" desire) or young children who have not yet attained knowledge of women's privacies, and they should not strike their legs (i.e., stamp their feet) so that whatever adornment they hide may be known. And repent to Allah altogether, (O) you believers, that possibly you would prosper.
These translations were taken from: https://quran.com/24/31-41
So most translations (except for the salafi Muhsin Khan) say pretty much the same thing. The argument here is that women shouldn't show their "adornments" or "ornaments" to anyone except mehram men and other women. "Adornments" and "ornaments" can mean anything, but as I have said in the past, it refers to body parts that cause sexual arousal. Hair does not cause sexual arousal. Women shouldn't show off those certain body parts, but also as I have said, you can't always cover body shapes. Body shapes and movements will ALWAYS SHOW no matter what clothing you wear. The point here is you shouldn't have the INTENT to show off and cause arousal, and that you shouldn't wear tight, revealing, or provocative clothing. If you are being modest and men get turned on by you, its not your fault at all. And then these translations also speak of using the veil or headcover to cover your body. Recall what I said earlier about Arab women at the time. Also the translations speak about only revealing what is "necessary". Why wasn't Allah more specific about this? What is "necessary" can mean anything. Hair can be interpreted as something that is necessary to show.
The next verse is 33:59. I'm not in the mood to show so many translations so we'll just stick with a few:
O you Prophet, say to your spouses and your daughters and the women of believers, that they draw their outer garments closer to them; that will (make) it likelier that they will be recognized and so will not be hurt. And Allah has been Ever-Forgiving, Ever-Merciful.
O Prophet! Tell thy wives and thy daughters and the women of the believers to draw their cloaks close round them (when they go abroad). That will be better, so that they may be recognized and not annoyed. Allah is ever Forgiving, Merciful.
O Prophet, tell your wives and your daughters and the women of the believers to bring down over themselves [part] of their outer garments. That is more suitable that they will be known and not be abused. And ever is Allah Forgiving and Merciful.
O Prophet! say to your wives and your daughters and the women of the believers that they let down upon them their over-garments; this will be more proper, that they may be known, and thus they will not be given trouble; and Allah is Forgiving, Merciful.
So same thing, take the over garments (already worn because its Arab culture) and cover the rest of their bodies which are exposed. The last part is about dressing in this way so that they could be now recognized as Muslim women, and not associated with the women who didn't cover their chests (so the non-muslim women) as well as slave women.
As a male, hair is not enough to get men sexually aroused. A woman's hair may or may not add to her being good looking. Often times it being covered or shown will make no difference.