3. A market for exchanging microcurrency and in-game currency. To me, this is the brilliant part. Love playing the game, but don't have cash to fork out? You can go to the market and put an offer in to buy doubloons (the microcurrency) with your pieces o' eight (Po8). Have some disposable income, but not a lot of time to go farm Po8? Go to the market and put in an offer to sell doubloons for a certain amount of Po8. The players set the market so this isn't just about dumping currency into the game, and the doubloons still have to be bought from someone, so this is something more games should pick up on.
I don't think this sort of trade is a good idea. To me, it seems like the people who are "good" at the game will end up playing for free with all the perks, explicitly subsidized by those players who are not good.
Second, from the companies point of view, the people who are "hardcore" about your game are also more likely to spend money on your game. But now they're not spending money on the game, but they are spending more time in the game. It feels like you are unnecessarily cutting yourself off from your greatest source of support.
Like, if you look at WoW, this kind of setup would probably mean that all the raiders would sell gold to the lower-end people. Raiders would be the ones playing for free while the casuals subsidized them to an even greater extent. That doesn't really seem either fair or wise to me.
I think my aversion to these schemes started because I used to play Magic Online. You had to buy packs of cards to enter tournaments. But if you won the tournaments, you won packs of cards. So the good players would "go infinite" where they never actually had to pay for the game, while the losers did all the paying. It struck me as pretty distasteful, and rather disheartening.
Now admittedly, most MMOs don't have that level of competition built in. The competition is more indirect. But it still strikes me as unfair to let the strong get a free ride at the expense of the weak.