The original fanbase did not react very well to any of this and Blizzard shut down the real money auction house as a consequence.
If 'what happened' refers to what happened to D3, as mentioned it was dumbed down to barely still be an ARPG, has an atrocious story, kills off Deckard Cain (since you do not know Diablo, he is an important / popular NPC in the first two, so this went across about as well as killing Leia in the 3rd Star Wars movie would have) and was initially very much focused on generating money via a real money auction house. GD on the other hand lets you build your char the way you want it (you assign the skill points), offers more skills, offers devotion skills on top and has a wider range of endgame gear / builds, so you can mostly come up with a good build of your own design rather than being forced into a cookie cutter build.
In any case, D3 is a very watered down ARPG that leaves very little decisions to you (attribute and skill points you gain when levelling up are automatically assigned, there are very clear sets for very specific builds, so either you end up with one of these builds or with a weak char). Not sure why you leave out the name of the company making D3, everyone knows which one that is.
