You allow players to add an after market effect to an item to greatly increase its value. However, doing so makes it bound to your account, and you can't sell it on the auction house anymore.
This can serve as both a tremendous sink of resources that players can work towards and a removal of valuable items from the market. (Because when the player eventually upgrades the item, the original item cannot be resold.)
Interestingly, there is not a RMAH, but there is a system to exchange ISK (gold) for subscription time that someone else bought. In other words the conversion of cash to ISK is facillitated - but not ISK to cash.
You could try to balance faucets with omnipresent unavoidable sinks aka. taxes. But how fun would it be to pay taxes in a game? "You loot 100 gold. Minus 30% gold drop tax. 10% dungeon upkeep tax and 15% financial transaction tax." :)
So the thing is: As soon as you try to model a "real" economy (possibly with real money exchanges) you can't have artificial faucets and sinks. Even Eve Online - which has the most advanced game economy - struggles with inflation as there are too many faucets. For such an economy to work you need to have a steady amount of money circulating the economy. And the only source (and destination) for money for players has to be other players.
But then you get a lot of other problems. Like what if a player hoards all the gold? Or if players just deactivate their accounts with significant gold sums on them? How do new players get their first gold? etc.
But most MMOs nowadays treat gold as something ethereal that you even can't lose when you get killed.
Just to point out that we're talking about game money here, not legal tender.
But in any case, I don't see why would it be dumb, as long as you value the time more than the money. After all, the same situation occurs often in real life, and nobody is considered dumb to pay for fish that he could've fished himself or tomatoes that he could have grown himself. Why would it be different in games?
(Personally, I just don't play games with grinding or farming activities, so there's nothing to earn or buy)
Hence, farming for game money to trade for an item rather than just winning the item myself means the game is ill-designed for me.