Here's how I think it works when it comes to sites like Facebook/Myspace:
As a eighth grader/HS freshman, you wanna feel cool and grown up and get a Myspace like everyone else to fit in. Then as a junior and senior, you see all the underclassmen CONSTANTLY talk about Myspace, so you wanna feel more grown up like your college friends, so you get a Facebook. And then once you're done with HS and college, you don't have anytime for either one and feel that you have no need for it, so you simply go for email.
So NOW I understand people's dislike for Facebook. I could be totally dead wrong :roll:, but that's how I see it.