In fairness, the real spearhead of IW left after mw2, which explains that somewhat. It's as if they've been told to remake the old ones out of spite to the folks who left, and because, let's face it here, they're making oceans of money re-releasing the same basic engine.
Also, Treyarch aren't nearly as bad. Black ops one was a quality game, and they patched it super regularly to make sure it never got hacked and whatnot. Was a top notch game.