It might have become an MMO cash cow, but there is no denying that WoW took gaming addiction to a new level. The exciting gameplay, vast story, and humongous scope of the human-player filled game world would set the genre benchmark for years to come.
The Witcher definitely deserved mention - as did KOTOR2 (if even as a post script to KOTOR1).
Demon's Souls should have been mentioned..Insane online gameplay, k@k hard which makes every kill that much more rewarding..
Personally while I loved Mass Effect 2, I found it a weak RPG and a great 3rd person action game.