pretty obvious that as video games evolve, and mainstream publications start doing more reviews, so too do the methods of evaluating them. The Simpson's Game seems to be one of those anomalies we're running into more frequently, where the game may not be all that to typical game review publications (and certainly not worth $60), but still presents an experience worth having (Heavenly Sword says "hello"). The games are neither evolutionary nor revolutionary for the hardcore, and so the reviewers give it a whatever score and move on to the next game they have to rate and berate.
Variety got a lot of flak for their Metroid Prime 3 review because it was written from a mainstream perspective. They pointed out to their average mainstream audience that Metroid probably isn't the Wii game for them if they don't know "the rules" of a Metroid game -- just think of trying to teach a non-gamer how to play Metroid compared to Wii Sports. In the case of The Simpsons Game, Variety goes and recommends an average game because they believe the writing could sustain their mainstreamer through the experience. While we frequently put gameplay above story, Variety and more mainstream pubs might see things reversed. It may not be all that simple, but it's plain to see that reviews can be influenced by the audiences they're written for.