I like wearing a hakama - I like the tight feeling around the hips (I also wear a wide obi for the same reason), it helps me keep better posture.
I'm not sure about Peter's 'safety' comment - anyone had a (non-trivial) hakama-related injury?
It explains a lot about Japanese food too - you really don't want to eat heavily spiced stuff when you wear one.
Isn't that the *real* reason many dojo's don't wear one until shodan? "OK, you think you're pretty good, now try doing all that while wearing a skirt".