There really is no doubt that Blizzard's Diablo III was really, a failure. It did not work on launch, had issues with DRM all through out and the Real Money Auction house simply detracted from the experience overall. The new expansion however, Reaper of Souls, looks to change that and more.
One of the main upcoming features of Diablo III and Reaper of Souls is the removal of the Real Money Auction house. This feature simply detracted from the core of the Diablo games, which is getting epic loot. What's the point of grinding these monsters if there is 40,000 of the sword you want out there for 5 dollars already? Sort of puts a dampener on things!
There is also an increase in the randomization aspect of Diablo. Players can go through portals, Nephelem rifts, which will have a completely random experience lined up for those who enter.
Will this get you back into Diablo? Not sure if it will pull me all the way back, but no doubt I'll take a look! Here's the trailer from Blizzcon