I think its because the common consensus is that lots of chicks are more "timid" or something than the guys. Back when skiing was all there was, and before expensive passes and high speed chairlifts and huge lodges and shit, chicks were about equal in numbers as men, however, the skis were retarded back then and they threw chicks on 195's. This kinda didnt allow them to progress much unless they were just REALLY good.
Plus, in the 90's the style changed and the snow was unpopular to women, and therefore they kinda ditched the sport...
now, there is a huge comeback. wait 10 years, and I bet money there will be some insane chick skiers out there... more than snowboarders even.