I have to agree with Kelimbror here. Nothing wrong with D3 or PoE for that matter. D3 is good fun and improved the base game vastly with RoS. If you just want a fun, mob smashing , loot acquiring game, D3, Torchlight 2 and Marvel Heroes seem like excellent choices.
Path of Exile seems really more for people with desire for complex and deep meta game along with their game. Any of the other ones i listed are much easier to just pick up and play. Personally i can't get into PoE as much as the others. Its needlessly complex (for me) for what i desire out of these sorts of games.
One thing that Diablo 3 leaves alot to be desired is the field of content updates. Sure we can argue if D3 even set out to do content updates but imo they could do better, considering they have a B2P game with a B2P Expansion, when Marvel Heroes or Path of Exile are completely free and push out content updates faster with a smaller team (this is an assumption on my part, those its well know that at least PoE has or had quite a small team).