I don't think it's exactly fair to say that every Call Of Duty since COD4 is a waste. I have spent so many hours playing MW2, Black Ops in Single player, spec ops, zombies and Multiplayer.
MW2 - around 100 Hours of multiplayer
BO - around 44 hours.
COD5 - Played SP (Bought it second hand anyway)
I am not a huge COD gamer, yet I have racked up enough hours of fun and hatred to justify the R400 price tag.