Blizzard monetized the game by selling it for $60 a copy.
That image you linked shows that the drop rates for items take into account the existence of the auction house. That sounds like a purely game balance decision. I.e., it would still be true even if only the gold auction house existed.
I never got all the outrage over the existence of the auction houses. In Diablo 2 you'd grind for hours looking for good drops and then have to spam chat rooms and trade with people. In Diablo 3 you'd do the same grinding but just for gold, and then you buy what you need on the auction house with that gold. What's the difference? (Other than in Diablo 3, once you're done grinding its much easier to get what you want.)
That image you linked shows that the drop rates for items take into account the existence of the auction house. That sounds like a purely game balance decision. I.e., it would still be true even if only the gold auction house existed.
I never got all the outrage over the existence of the auction houses. In Diablo 2 you'd grind for hours looking for good drops and then have to spam chat rooms and trade with people. In Diablo 3 you'd do the same grinding but just for gold, and then you buy what you need on the auction house with that gold. What's the difference? (Other than in Diablo 3, once you're done grinding its much easier to get what you want.)