I don't actually have an answer, other than: Most people's intellectual and emotional development seem to freeze around sophomore year, as far as I'm concerned. (I didn't say I wasn't a snob. I despise intellectual laziness and apathy. Get over it and read a book, m'kay?)
Most of the people I love, are incredibly passionate consumers of art and information. The ones I really, really treasure have no filter that says, "I can't like this, it's uncool." When we stop being sheep engaging in reflexive snobbery, I think we'll be a lot happier. We'll also get better entertainment and culture. Mix it up friends, read silly things, read high art, (for fuck's sake: READ, will ya?) Listen to pop and classical and rock 'n' roll. Share your tastes with your friends and don't worry if they think something's a little kitschy. Maybe they'll find something they've never heard of and love. Maybe they'll share something you never knew existed. Cultural show and tell, it's about freakin' time. It's the 21st century, the old rules don't apply. Start acting like it. After all, you're not in high school anymore.