its a taste issue... i dont go for the Serious Sam stuff anymore... I got enough of that with Duke 3d...
I guess that's always been the point with id software, Carmack
has mentioned that the FPS is primarily a genre of action, and well, shooting. He descibed it like basketball, the concept of basketball doesn't change, people don't keep making different kinds of basketball games.
I suppose that's why they don't expand on the FPS concept much at id, AND I'M FINE with that. Go play a top down strategy game space ace.