cod4 is still considered the best competitive fps game in this current gen.
The problem with just making yearly installments of the same game with tweaks (and regression) without actual investment in the competitive scene while being the fps series powerhouse makes the whole genre look more like a joke in the competitive scene.
I mean look back when Quake and CS were the games for competitive fps, and now compare that to what cod has added to that (or lack of adding). Basically every scene has improved, grown, and expanded (rts, fighting games, moba), while fps has become stagnant due to (imo.) cod.
I mean its not to say competitive is everything, but when the genre was built around the competitive scene for much of its history, you would think that modern developers would try to stick along that path, not regress to help the genre in the long run.