Every season in D3 has its own thing though, last season were super powerful ethereal weapons and the upcoming will have soul stones with their own unique abilities. So there is always something, and sets are sometimes reworked and stuff like that. Pretty good for a game without microtransactions, I'm really surprised blizz keeps it going for no profit outside of MAUs.
That said, the fun thing with it is to play for like a week or two every 3 months. It's a quick intense experience for almost everyone who plays it.
It will be interesting to see how it works out in wow but I'm sceptical. The quick and easy concept doesn't really work here. I'm guessing people will play it for one and maaaaybe two season but not more than that.