Looking at the last few expansions to WoW (Cataclysm, sadly, did not meet my expectations and made the game boring for me, more on that later), I've noticed a steep drop in the value of gold. Just in grinding out from 80-85 I made quite the load of gold, and there aren't that many drains in the economy. Training and the like is a big one, but only flying mount training (for fast fliers) and constant respeccing of talent points (I mean ludicrously) could be considered a balancing factor for the massive gold values we are now seeing. This is driving inflation so badly that you don't need to know even how to spell economics in order to spot it.
Is this a bad thing? Ultimately yes. One good result is the dying off of gold farming as a direct industry. You do not need hard to obtain amounts of gold for anything save buying the best equipment. Gold is also not difficult to obtain at all, increasing the supply. More supply, less demand, yields lower prices. It has reached the point where "human" gold farming, even in the East, is not profitable. This is a sad turn-around from an industry that was making boatloads of money off of the market. They are simultaneously suffering from a lack of power levelling need, as Blizzard made the game so much easier.
Now for the bad results. Newer players, and those without a lvl 85, have trouble even on developed servers 1. finding goods and resources they need and 2. finding them at reasonable prices. Things tend to balance out a bit, but not very evenly. If simple resources are ridiculously expensive, then newbie crafters cannot buy them, but newbie gatherers make bank off of them. This goes up and down the "brackets" until a balance is found, usually at a point where items up to say lvl 40 or so are super cheap, and after that are super expensive, leading to the difficult choice of grinding out a gathering profession to sustain your character's wallet for 30 or so levels until gold becomes easy to find.
A secondary problem, and one that will continue to get worse, is that with few drains, inflation will just continue. Soon it will get to a point that even newer players or players who don't grind out money will not be able to afford anything. This will lead to gold farming being a viable industry again, which, if Blizzard's goal was to kill it, will be counter-productive. If you need 100k of gold to buy a good item, and you can earn 3k gold a day, are you willing to waste a month of your time, or would you pay say...20 dollars cash in order to have it?
The third problem is the sheer "free money" aspect that guilds now have after they get their traits. One line of these traits generate additional cash from every looted amount that goes directly to the guild bank. Now, I've seen the direct result of this at low levels being a nice fund for discretionary spending, and realize the effects of it being used to pay for raid repairs and the like, however, this is removing a further drain on the economy, *and* generating even more money. This is essentially adding a 10% or so boost to the inflation rate, probably compounded even more by the fact its use is almost solely on economic drains.
Solutions to this problem? I frankly don't see any. We are in too deep with this system. Its a similar problem to the rampant increase of stats with each expansion, you cannot remove it without players getting mad. One option is for blizzard to introduce something that is a further drain on resources. An idea I will bring up again is the idea of guild bases. These should be something that is fairly expensive to create, requiring money to maintain, and subject to guild vs guild pvp. Not saying that is the only solution, but there needs to be something for all the money to be used for besides player to player trading. I would discourage them from using just an item worth x gold as a "drain" as it is a cheap way out, and would create more problems as people grind gold towards getting it.