Oh come on, how can a whole group of people be wrong?
I was really hoping to see a bright pink one in there, lol. That site was good for a giggle...especially this one:
Hehe.
As for the original question, I really hope they're not a "must." They make me think of those all-in-one-pajama sets that kids wear where with the feet are covered and they zip all the way up (what are those called? I can't remember now). I think it'd drive me crazy trying to wear a one-piece ski suit like that.