Have you ever thought that Capcom thinks it has the GCN market "under control" and so it gives us some games that are sure to do well, like RE4, Killer 7, and Viewtiful Joe, while the boys at Capcom go "work on" the PS2 and GCN markets? RE and RE0 have sold well on GCN, and RE4 should easily do better. All Capcom really needs to do is make some commercials for those three games I mentioned...PN03 I don't see much light in.
Anyway, they need to release more games on Xbox and PS2 so they have a better chance of scoring a hit. Besides, notice how the PS2 and Xbox games are generally more low profile and low budget compared to the GCN ones - they can afford to make mistakes that way as long as a few of them do well...
I'm sure Capcom has thought this out already...