You think critics are objective?
You think they want to pan the people handing them early review codes TOO hard given that it is how they make a living?
Often critics have little time to review a game, a few hours, etc... they have a ton of games to review, they'll use cheats in single player games, or play through on easy mode etc.
For a game like D4 that is played at the end game, and really the big problems will only show up later in the game... There's no way a review was going to be right.
Understanding what a critic can, and can not see is critical to understanding what they can tell us about a game. Personally, I give them some weight, but I've taken to waiting a bit and listening to people who love the genre speak about it.
When Raxx is panning D4... it's bad. Bad enough that 79 is a WAY overrate.