This doesn't actually get money out of the system. If I sell you my WoW account, money has changed hands but none of that money has come from WoW/Blizzard.

There are some game developers looking at sanctioned RMT right now because it would be a huge selling point. "Make money playing video games" used to be a popular slogan on tacky banner ads. That could see a comeback in a different way.

Sanctioned RMT works through some official marketplace (think Diablo 3's ill-fated Auction House). Not only does the developer not pay out anything (all money flowing through the auction house is coming from buyers of items), but they even take a "transaction fee" cut. All while continuing to own all the items being traded. There's no downside for the "house".

Except perhaps suddenly running afoul of gambling regulations if they can no longer argue there's no "prize" element to the gambling?

I see that definition expanding.

We're well past the point where virtual entitites are imaginable by the general populace.

Getting a virtual gun, creates an actual advantage in the game your are playing online.

While ultimate ownership of the code may be fraught, but practical day to day ownership and usage is not (unless you are fighting a particularly contrived case).