This has been driving me crazy. People bitching about the game and the lack of content, patch release speed, Blizzard doesn't care about the game, blah blah blah.
Diablo is not subscription based. It's a once off payment. Whenever Blizzard releases a patch, which they do every couple of months, they make no money from it. People might come back to play but they don't make any money from that. Some new players might get dragged in by friends coming back but nothing major. After they released Diablo they were under no obligation to do anything else with it.
What other single payment game releases new free content and updates 2.5 years on? Blizzard is a company at the end of the day so of course they are not going to put all their resources into a game that makes them no money after you buy it initially.
Another thing is playtime. "I got bored after a few weeks." "I ran out of things to do after a month." So what? Diablo is not an MMO so stop treating it like it should have new things to do all the time to hold your interest. Look at your playtime vs other games and also count the number of times you have returned to other games.
I can understand complaining if you didn't enjoy Vanilla Diablo or Reaper of Souls when they first came out. You spent your hard earned money on those but everything else is basically free DLC.
TL;DR Stop bitching about the slow release of free content for a game you bought years ago. It's like getting a free car and then complaining about the quality of the car or why you didn't get it sooner. IT'S FREE!!