I don't generally see a lot of people below 13 years old nowadays, me living the cloistered life that I do. The closest I see is my girlfriend's little brother. And he dresses a lot like I did when I was his age - normal blue-jeans, and a t-shirt featuring my favourite TV show character that week.
Now, I don't see a lot of girls under the age of 14 (or whatever the hell age they are in grade 9). But I don't see the problem you people seem to see. They wear pretty much the same thing they did when I was that age - which is also pretty similar to what the guys wear: jeans, t-shirts, etc. Sure, their fashion sense would make a blind gay man cringe, but then so would mine. I don't see the problem everyone else seems to see. Must be my region. Southern Ontario isn't exactly the wildest part of the continent.