I really think I've figured it out, why people become so goddamned dull as they get older. I'm seeing my own war against it, since I turn 26 soon and slowly approaching my 30s. You reach a point when all your favorite songs remind you of someone you'd rather forget, and after a certain point, these are the only songs you'll listen to after 12:00 on a weeknight. Therefore you go to bed earlier, just to get more sleep and avoid thinking about all your ex-girlfriends.
Yes, I know...Mike's hare-brained theory for the night. Enjoy it for what it's worth.