Games should be relaxing, or barring that, at least fun or entertaining. That's perhaps one of the biggest rules in game design: Make it someone people will enjoy. Unfortunately, little can suck more fun out of a game, than when $149 evaporates.
Diablo III's Real Money Auction House has been a hassle ever since the game was released. It was repeatedly delayed to make sure there were no bugs. Unfortunately, ever since there have been a few bugs that have gone public while gamers wait for a return on their money or in game item. The first issue was resolved, but the second so far has not been.
Much of Diablo III's design is based around the RMAH. We were told the always-online DRM style was to protect consumers looking to use the RMAH. The GMs also artificially limit loot drops to maintain the economy.
With a large portion of the game devoted to a component that was delayed, buggy, and manipulated, it's no suprise, then, that the game's user base has dropped by about 50% since launch. We were promised so much if only consumers would be patient with the real money auction house, but unfortunately it so far has failed to deliver.
It should be in Blizzard's best interest to fix these problems ASAP. They get at least 15% of every transaction in the RMAH, and even more if someone wishes to pull their money off their Blizzard accounts. It's how they can keep users, and keep the game sustainable at the same time.
In all fairness, some bugs are understandable. Is any large enough system, you'll have issues of glitches and unsatisfied customers. Blizzard, however, have been too slow in resoving these issues and put too much red tape between the standard user and the game masters who can take care of everything and refund the money.
For now, it's best users either avoid the RMAH or be warned that money put in may not necessarily stay that way. Diablo III does have a lot more to offer aside from the auction. Unfortunately, they just put too much stock in it, and it has hurt the game as a whole.