I was like you before I got a 360, and more recently a PS3. I was also a blind Nintendo fanboy, and I used to say "Pfff! Games are already replayable enough if they're well made." Sure, that's right, but you can also get rewards (and sometimes in-game rewards à la Uncharted) for playing a game you love? Sign me in!
Random game thought :
Why is Bionic Commando Rearmed 2 getting so much hate? We finally get a real game and they're not even satisfied... I'm starting to hate the gaming community so f****** much...