It's pretty dumb. It's really unsafe and if you were squatting anything serious you could risk snapping the heel of the shoe. It'd also be pretty awkward performing the squat. I've never worn high heels and I'm not sure of the weight distribution, but having your feet at an angle is bad news bears.
If anyone could find a citation for how weight is distributed in a high heel that would be interesting. You generally want to keep your weight on your heels when squatting, so it'd be cool to see if high heels force the wearer to keep weight there, especially when the go down to squat.