The problem was that while World at War was a rather good COD game, it was released after Modern Warfare. MW had set the bar quite high, both with its excellent singe player campaign and with its modern warfare multiplayer that attracted a lot of the Counter-Strike crowd.
Modern Warfare 2 was a bit of a test, the game would sell on its name alone and therefore certain strange ideas could be tried. Despite all the rantings and anger, the game broke records with its sales.
I suppose Black Ops will be successful, especially if the part of dedicated servers and the lean action will be included. I bet that even the grenade launcher will be back to irritate the people.