As in other cases, the Wii throws a monkey wrench into the whole system of exclusives, because it's very hard to make a game cross-platform between it and the others and get some sort of parity out of it, so often the exclusives argument can just be reduced to PS3 vs 360, where it is still relevant
Within this more limited field of PS3 vs 360, it's not about bad exclusives or good exclusives as it is about big exclusives, which i suppose would be defined by hype and the weight of their franchise. Thus, Haze was a big PS3 exclusive (hyped greatly, though popularly regarded as a bad game). Big exclusives are what give a console it's weight, which isn't exactly tied to quality (though it often is)
But in a wider view, putting Wii back into the picture, the problem just becomes murky, between the Wii's countless, horrible exclusives, as well as its rapidly growing field of good-but-little-known exclusives, and its small field of big exclusives, and the fact that with the wii's strategy "big" no longer has much meaning.