For dedicated players, every new generation adds quite a lot, for example, in generation 3, natures were added, this made breeding a much more important part of competive playing, also, with online in gen IV and V, the competive playing has been vastly expanded, gen V was by far the most sosistiphicated( I did not spell that right) story, plus, "serious" players have to rethink their strategy in every gen because there are new pokemon and moves to take into consideration, also, gen V expanded massive on the online part by having Dream World and entralink. I feel that every new Generation give me enough new stuff to get the game. I haven't played much CoD (only MW and Black Ops) so I don't have much to say there. I think the biggest problem people have is that they don't like Cod in the first place.