Why can't they, are they paraplegics? or do you hang around with minors? :p
Everyone I know says: "WOW that's SOO cool! Whats it like?" then its 1 of 2 statements: "I want one, but I like the safety of a car." or "You're DEAD if you get into an accident, you'll never catch me on one of those" Read: The novelty is cool, but the required state of mind must be psychotic.
I could care less what they think, personally. None of my close friends ride (except my woman :)), and maybe 3 close associates have bikes, whom i have yet to actually ride with.