I endorse exclusives when they make sense.
MGS4 doesn't make sense. Gears of War doesn't make sense. Ratchet & Clank doesn't make sense. Splinter Cell doesn't make sense.
It makes sense for your game to reach as large an audience as possible, it makes sense to get as much profit as you possibly can, it makes sense to create the game you want to create.
My personal dream scenario would be that you had one console, like a DVD player. Microsoft, Sony, Nintendo, Samsung, Toshiba and more could all create their own versions of the hardware, but any game could be played on any of these hardware iterations. The differentiator would be what every other offering that console gave you. If I wanted the best online service, maybe Microsoft would be the best choice. If I wanted additional TV offerings through my console, maybe Samsung would be my best bet. If I wanted the best stereoscopic 3D, maybe Sony's version would be the one to get.
My pants are wet from the thought alone! 
In general though, what we can say is that hardware performace is not what drives sales or creativity. It's interfaces and features. The exclusives that make sense this generation are not God of War III, Fable 2, MadWorld, Super Smash Brothers Brawl or Halo 3. They're Heavy Rain, Flower, Demon's Souls, LittleBigPlanet, Red Steel 2 (I know this list looks biased, but my knowledge of unique games on the Wii and 360 is limited, so bear with me) and games like them that make good use of the console's respective abilities.
If the hardware manufacturers had to fight over my money on features alone, I think we would see a hell of a lot of growth in the industry, and I think all developers would be able to produce better games and take more risks. Imagine if the current gen consoles had all been "one" console. They're would be room for much more innovation and risktaking on a 145 mio. userbase as active as this one, than on any of the platforms we have today.