You are not understanding the Islamic concept of modesty. Islamic modesty isn't about fading into the background and being plain and unnoticed. It's sexual modesty, full stop. In the west, when we say modest, we usually mean someone who is plain, humble, not flashy, etc. It doesn't mean that in Islam, esp. with regards to the hijab. While there are, in some schools, rules about flashy hijabs, generally Islam has no problem whatsoever with luxury or women wearing colorful clothes or standing out.
In fact, the quran, in the passage used to support the obligation of veiling, tells women that they should cover with cloaks to be known -- to be noticed and singled out and set apart as Muslim women.
Comes down to whether people genuinely
want to be modest (and if they did then I'm sure they'd know how to dress to avoid raising eyebrows), or if they're dressing in that way for religious convictions, which is completely fine, but I wouldn't dress like that under the rhetoric of "modesty" because I'm sure they understand that jaws drop around them.
What I'm saying is that if a person
truly wanted to prove their modesty then they wouldn't be drawing attention to themselves, would they? I understand that Muslims who wear the niqab may do so for sexual modesty as to not reveal skin, but it doesn't change the fact that in a Western society where they're probably living in, the idea of modesty isn't to attract attention to oneself.
By all means, if they wish to call it remaining pious or devout, or practicing religious or cultural customs (it's hard to tell sometimes), then that is absolutely fine. What I'm saying is that to anyone else in a Western society, the niqab is about as immodest as it gets in terms of trying to reflect attention away from yourself.
From a logical standpoint, if we're asking people "do you want to be modest by blending in or modest by standing out?" then the answer from a person who wishes to be modest is that they want to blend in or dress conservatively rather than wearing a cloaked billboard for religious devoutness. Whether it is religion or not; that just defeats the purpose of trying to dress modestly in a society where no one dresses like that.
Topic: Your experiences of the niqab/burka?