I guess, to me, if they're dressing in the same style as everyone else their age, then they're adept at conforming to fashion. While they may need a guidance counselor's nudge to begin with, they won't have a hard time figuring out what to wear in a business setting where more formal clothes are expected. Remember it's just fashion.

It's a bit personal, just because my parents dressed me and my sisters like we were in some kind of weird TV cult, and we had to figure out how to dress ourselves when we were in our 20s (middle sister never did figure it out - she's a college professor with an emphasis on fieldwork, so she can get away with it at work). I'm just barely, I choose very conservative clothes just because I never learned how to accessorize, match or flair. I think if a kid has the social networks they need growing up, then basic conformity to fashion won't be hard for them - whether it's pushing the edges in high school, or rocking a suit at the office. If they don't have that social support, then punishing them for what they wear isn't going to help.

Plus, I think there's a world of difference between "X amount of cover is required in a setting with Y level of formality," vs "girls have to cover because boys can't help raping them if they don't."