Blizzard didn't just shut down the real money auction house, they shut down the gold auction house as well, moving all item trading to an in-game, 1-on-1 interface.
More importantly, they made all Legendary items account bound. That means no trading of Legendaries whatsoever, even with the friends you play with. Want to try one of those item-based play styles? You better find that specific Legendary yourself, and it better have good stats, because you can only re-roll one stat per item, and without good core stats an item is useless no matter how cool its power is. Blizzard has thrown the baby (item-based play styles) out with the bathwater (large-scale trading, whether on an official or black market). To highlight the futility of collecting all interesting items yourself: I have still never found a set item in Diablo 3. (In Diablo 2, I found the entire Sigon's set myself, without trading, and used it on low-level characters.)
Blizzard is obsessed with their "reward loop", which I admit is a pretty nasty-perfect skinner box. But the true reward should be epic, heart-pounding battles with varied challenges. To get a feeling for this, try playing hardcore. I mostly play HC, so the softcore-only, real money auction house was never really an issue for me. Now that we have Loot 2.0, especially after the expansion was released and opened higher item levels, it's trivially easy to build a character that has a chance surviving pretty hard settings (Torment 1) just by cruising fast on normal difficulty and constantly upgrading with boring, Rare items that have crazy >60 level stats. But I suspect it's even more impossible to build a character that can survive the highest settings in the game (Torment 10).