If you're a Halo fan, do you lose anything knowing that the game now exists on the PC? Would Halo 2 be a worse game in your mind if the PC version game out simultaneously with the Xbox version? Would Prince of Persia be a better game if it only existed on one platform instead of all of them? Did KOTOR all of a sudden become a terrible Xbox game after it came out on the PC also? If you answered yes to any of these questions, you may want to consider therapy. :)
I find it depressing that people feel the need to carry some kind of banner for their chosen platform, buying into the marketing hype of "Only on Xbox!" or "Only on GameCube!" as if those meaningless labels somehow make a game better. Because that's all it is. If you truly believe that "exclusive" games are inherently better than a game that happens to exist on multiple platforms, you're either delusional or you're a marketing executive's dream, as you'll probably buy into most anything they tell you.
I'll listen to the argument that [game x] should have been Xbox Game of the Year because it was more original/fun/challenging/old-school/popular than Burnout 3. But if your argument begins and ends with the fact that Burnout 3 isn't an Xbox exclusive, and that should somehow disqualify it from contention as a certain platform's game of the year, then I weep for you because there is absolutely zero logical ground to stand on there. "Oh noes! I can't like Burnout 3 because those dirty Playstation 2 owners are enjoying the same game!" That's just sad. It's also funny because I don't see anyone using the same argument against San Andreas even though that game will be multiplatform in a matter of months.
And if I sound really crotchety and cranky about this it's because my sleeping schedule has been completely thrown off thanks to World of Warcraft. Sleeping at 8AM and getting up at 3PM = no good.
Hey at least I still have like 30 hours to do all of my Christmas shopping...