I have a lot of sympathy for Jay Wilson because I believe that he was given a basically impossible design task: he had to somehow design a fun game around a real money auction house.
The only way for the RMAH to work was to make it nearly impossible to get good items from monsters and force the use of the RMAH, so he had to design to a fun Diablo game where it's incredibly unlikely to see good drops. Think about how ridiculous of a design challenge that was.
Blizzard forced the RMAH onto this game. It wasn't Wilson's choice. I really don't believe this game can be saved without removing the RMAH. If you look at the stuff he actually did have control over, such as the feel of the gameplay, the visceral combat, and stuff like that, those parts of the game are quite excellent. Diablo 3 actually "feels" better than every other action/RPG out there. The feedback on the Barbarian's attacks, in particular, is fantastic. The only design element of Diablo 3 that I really hate is that there isn't a "no dialog" option that you can choose. In a game like this, where you farm the same stuff perpetually, it's ridiculous that you have to skip through the obnoxious dialog boxes forever. That was a colossal mistake.
Having said all of that, though, I'm still not really sure how Wilson got this job in the first place. He really didn't have the history or background for a game as high-profile and critical as Diablo 3.