Well, you could say the same for a large proportion of guys (fearfully close to generalising, but whatever) who prefer the toned look over a chubbier girl.
I'm by no means saying this is what all guys think, but when you have a lot of guy friends that have no qualms in pointing out a girl's so called flaws, (because, shock horror, every girl hasn't got the svelte physique of an Amazonian dancer) it appears this is the preffered look. Slightly de-railing here, but I only know a handful that think otherwise, and mostly, this is because these sort of guys are the unripped specimen who can't afford to be too choosy.
To answer your question, some girls do, some girls don't. The media does a lot to make these sort of images attractive to people though, so that's probably why. And plus, women, (and men,) instintively look for a healthy partner - an attribute that is often reflected through a decent physical appearance.
Ah, society.