“The problem is these girls are rebelling to some extent or just dont care, it doesnt bother them.
The question now is, why, how?”
Very simple, actually. I think I may have heard the refrain that a Bas Yisroel is supposed to be “Attractive NOT Attracting” a million and a half times. Problem is we as humans are hard wired to want to attract the opposite gender, and by dressing a certain way, even if it is -1 inch here and there we are getting positive feedback from our male counter parts.
If the boys started not liking it the girls would stop doing it.
It is really that simple.