Rainbird on 03 January 2011
I think evolution in the content is necessary, or else a game will be too samey and be slammed for it, but the degree of evolution needed can be very different, depending on genre, developer and franchise.
And Assassin's Creed: Brotherhood (which you mention for lacking evolution) brings multiplayer to the franchise, and does it well too. That's a huge evolution in content, even if the single player component shares a lot with the previous game.
Other than that, I agree. 
