Former
Diablo III game director Jay Wilson admitted the real-money and gold auction houses "really hurt the game," as Blizzard underestimated the number of players who would turn to auctions to outfit their characters.
Joystiq has details from a GDC talk where Wilson said they thought the auction houses were a service players of their action/RPG sequel wanted, and that hosting them in-house would reduce fraud and abuse, but as in the end, they created an environment where collecting money was a primary goal over defeating Diablo and his hordes. He also says they would turn off auctions if they could, but they have "no idea" how many players this would disappoint. His contention that Blizzard thought only a small number of players would use the auction houses is hard to fathom in light of the game's design, which, for a considerable time before a series of balance changes required the very best gear to complete on the highest levels, even though such gear dropped so rarely it was impractical to try to collect it without using the auctions. Blizzard has a
GDC talk scheduled for today discussing their iterative design process for Diablo III, and their preview of that mentions a number of systems that were reworked during the game's design because they were unsatisfactory, but all the examples they use are gameplay mechanics, and not things like auctions.