You know, I think you're missing a piece, which is about the hypersexualization of girls. Girls that age aren't talking about not doing their math homework because they want to look pretty for a boy; they're talking about this massive pressure that is driven by multi-billion-dollar marketing that you have to look and be a certain way. It's a very sexy way compared to what it used to be.
That's why I was saying it's not just about having to be pretty; it's about these very confusing messages for girls who are nine, ten, and eleven years old. Why are we selling lingerie to them? Why are nine-year-old girls able to buy push-up bras? What's that image? Rather than that they get interested in the opposite sex, they're fighting off this bombardment of media messages, and that doesn't leave a whole lot of time and room for other pursuits and development.