G Gordon Liddy's wife, Mrs. Liddy (God rest her soul) had a theory about this, and the fashion industry in general. It's strange, but somehow makes sense.
If I remember it right:
In a nutshell, the fashion industry is run (mostly) by gay men. They see women (strangely enough) as their competitors. And, some of them being freakshows themselves, they're attracted to 10 year old boys.
So, they find women with bodies like 10 year old boys and call that attractive, and they hope that straight men begin to find these stick figures attractive. And have women to strive to look like these stick figures. In their mind, it's their "retribution" against straight men for being straight, and against straight women for being perceived competition.
As for them being ugly as a box of frogs, I think that's the women designers' insecurities about their own beauty manifesting itself. They can't have any woman prettier than they are around them.