Back in the Nintendo and SNES days, back when online multiplayer didn't exist besides on PCs, gaming was much more fun. The reason, I've deduced, is because back then I played the games for fun..there wasn't really much there in terms of competition - yeah you had your friends to play with or against, but the majority of the multiplayer games were co-op, so you weren't really competing as much as helping each other out. Now, I play majority multiplayer games..and I'm so worried about being better than the next person that it's less of an enjoyment and more of a chore, I guess. Even the single player only games like Uncharted aren't as fun as they would have been when I was younger because now all I can worry about is being able to say I beat the game on the hardest difficulty instead of playing on, say, normal difficulty and just enjoying the game.
*edit* I'm not saying I don't have fun playing games anymore, because I do. It's fun to play online with my friends on XBOX Live and everything, but a few of my friends are super-competitive to where if they have one bad game, they get pissed off and quit - even mid-match..then I get aggravated and it kind of ruins the vibe. There are times when we can all play Call of Duty 4 for a few hours and just have a blast, and that's the only time that I really feel the same enjoyment that I used to. Unfortunately, it doesn't happen much anymore. Also, as much as I'm not the biggest fan of Rock Band-esque games, playing them with my friends can also be pretty fun when we're all sitting there joking around and just not taking it too seriously.