Some time ago I mused that the primary fun of playing a goblin in a game like WoW was that each server represented a relatively small market and as a result there were plenty of openings and opportunities for quasi-monopolistic behavior. Between this and going over the perceived issues with Guild Wars 2's trading post, I've been asking myself what I would want to see in an MMO market.
With most MMO's, the market seems to eternally caught in a spectrum between "realistic" and "convenient" because real world markets are in part motivated precisely because they are inconvenient. Goods exist at point A but you need them at a factory at point B. In some games, like EVE, this need for logistics is hard-coded and some enterprising players have figured out how to make good money acting as the UPS of New Eden.
On the other side of the coin, the big name fantasy MMO's take a model of convenience instead (ironic that the medieval ones are eliminating the logistical issues). At most the inconvenience one experiences in Guild Wars 2 or World of Warcraft is having to walk to said market (which is usually less than 2 minutes away using a hearthstone or teleporting) and then to your mailbox or another nearby location to retrieve your goods. A few games, such as Final Fantasy 11/14 and Ragnarok have allowed for players to become "shops" and locate themselves somewhere in the world; and personally I like the idea. However the presence of a convenience one-stop-shop auction house somewhat overshadows the positive from this idea.
So where does the line get drawn? We're essentially choosing between "Realism" and "Convenience". The former also often seems to create the niche markets and divided ones (such as individual WoW Realms, or the regions in EVE). While the latter is better received by players who don't want seemingly "artificial" barriers to their fun. The problem with having a strong economy on the latter is that it makes "flipping" (taking an underpriced item and reselling it at a higher price) rather easy....too easy..."click refresh and buy what you see" easy.
Perhaps making me a bit of an island in the MMO market, I'd like to see an MMO that eschews the auction house model. I would like to see a market that is a little more towards the "realistic" side in a game. I'd like to see a fantasy MMO where the crafting/economy are connected. Much like EVE, but with swords instead of ships. Perhaps each player could be the "store" (like in FFXI) but add an easily navigated menu of all the "stores" in your general location so you can find them more easily. The idea being to make crafting as much about finding the ingredients as it is putting them together.