Melissa, don't you think another possible outcome of your suggestion is that females might feel pressure to do something they don't want to do? If other girls their age are showing more skin, there can be tremendous pressure to do the same, even if they don't want to.
Teens are followers. Some school districts started requiring school uniforms because of the pressure students were feeling to follow the crowd and dress in ways that maybe they couldn't afford or didn't like. Students themselves later said that they like the unforms, because they took some of the pressure off that they had felt before.
If the trend became "showing more skin", then flat-chested, overweight girls or others not comfortable with nudity might feel pressure to exhibit themselves in a way that they feel uncomfortable with or like they don't measure up (I know when I was in high school and was this toothpick of a boy, I wouldn't have wanted to go shirtless or even wear a tank top around the buff athletes and others with larger, muscled chests, shoulders and arms. Gym class was hard enough!). As adults, we can resist such pressures, but teens especially have a hard time doing their own thing, as they want to fit in and be accepted.
I think we should de-sexualize the school environment as much as possible. Let kids be kids . . at least those who aren't in such a hurry to have sex and seek other adult pursuits. I always said to my sons and their friends, "Enjoy being a kid. You will have a long time to be an adult, and you will probably look back on your youth and wished you hadn't hurried through it."