High quality materials to avoid chafing in certain spots, drying off quickly and just being comfortable in the water. If you don't surf I could see why you wouldn't understand it compared to some other bathing suit. That being said, they are expensive. I normally buy a new one each summer and use my old ones too. After awhile they're so caked with wax, sand, and salt that it's time to get some new ones.
Dude, joke's totally on them, you should make a t-shirt that says 'all you fools suck' and on the back it can say 'I rule coz T-dawg said so' and yeah, you'll be rockin it shibby, new steeze brah, wikkid! ~PhattTim