Fully agree. Bought D3 at launch, played a bit. Meh.
Came back after the real-money AH was gone, then played the expansion - have sunk many hours into it since then, coming back again and again for a week of play in a fresh season. It's a good game now. And I like it a lot more than D2, that always felt too grindy and I hated that there were no talent resets. (AFAIK they added them at some point, but not when it was current.)