I personally do not like their styles as much as I used to, lol.
Most Helpful Girl
Because they don't want "fat" girls wearing their clothing. Their market is preppy, popular, thin girls. If everyone can have something, it loses it's "coolness"---in order for something to be cool or popular, it has to exclude people.
But don't fret; not being able to waste your money on overpriced clothing that makes you look like a walking-billboard is nothing to be upset about. :)