No, the young girls are dressing like Britney Spears because their parents and teachers don't want them to. It was same reason I started smoking cigarettes and pot when I was 12. All kids rebel, each in their own way.
I've long since wisened up and stopped both, but the point is is that even though I knew that smoking was bad and that pot was illegal, and had been told my entire life that I shouldn't do either, I did it anyways...
I won't even get into the oppression of women in other cultures, (they get oppressed enough here as it is, just not as blatantly), but...this goes back to our backwards and patriarchal views of sexuality. I wouldn't want my kids reading a Playboy, but mainly because I don't want them getting false impressions of what "beauty" is (with the airbrushing and whatnot.) This would be where I start going off on gender roles and expectations in society, but that would a needless tangent.
Society, in the end, is what determines what is "Bad" and what is "Good". Interracial Marriage was once considered against God and a Victorian Woman showing any more than a calf was considered a whore and a harlot. Hopefully, one day, we'll overcome the dated, post-victorian mores that say that men can sleep around, but a woman is whore if she wants sex (we've made progress, but not enough), and we'll stop treating nudity like a crime and sex like a sin, and Rockstar can make a game where you have sex and not get Congress riled up.