I'll use Assassin's Creed as an example. Imagine if this game were exclusive to the PS3 in the exact same form that it was released in. Don't change a single thing. It would be used as fodder against the 360 at any given opportunity. The exact same game, mind you, but people would swear on their grandmother's soul that it was too much for the 360 to handle. Who could argue? I mean, the 360 version wouldn't exist to prove the comparable power of the 360 and PS3.
But the 360 version does exist. The 360 version of a lot of games exists--and sometimes, that version is the better version. You STILL have people saying that the 360 version held the other version down--often with as much proof as I have here proving the opposite (which is absolutely none at all). The basis for this, in my opinion, is an absolute NEED to have superiority over the competition. I don't get it.
Imagine a world where a game like Mass Effect 2, Bioshock, or Ninja Gaiden--games that were once exclusive to the 360 were originally on the PS3. Imagine the amount of rage there would be if they were ported to the competition--after development for the PS3 version was totally complete. None, you say? If Konami said MGS4 was being ported to the 360 a full three years after the PS3 version, PS3 fans would say that it somehow hurt the quality of the older version! Where does this come from?
I've played and enjoyed games like Little Big Planet, Uncharted 2, and God of War 3 on my PS3. If I were solely a PS3 owner, I'd be glad for my friends on Xbox 360 to have a chance to play the game. When ME2 was released for the PS3, I was happy that PS3 owners could finally see what 360 gamers were clamoring about, all along. Nobody shared my sentiments. Suddenly, ME2 was "shit compared to ME1 which is only on 360". ME2 "didn't hold a candle to the PS3 exclusives". All of this hate because suddenly the game was available to a new audience. Sometimes, fanboys make me sick.
Look, I personally don't see the point in exclusivity. I don't get a sense of joy when the Blu Ray version of Avatar (just an example) isn't available to DVD owners. I'm glad they can see how shitty avatar is without the 3D! I don't get any pleasure talking to my PS3 owning friends at work about some call of Duty Map Pack that they don't have yet. I wish they could join in the conversation. I don't see the huge technical leap between a game like Uncharted 2 and Batman AA. The PS3 and 360 are about the same to the average person. I think a comparable version of God of War 3 could be produced on the 360.
So, I posted all of that just to say this: The only reason people care about exclusivity is pride.