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In regards to EQ2's Exchange servers, which the OP's post mimics.
SOE stated that it saw a minor reduction in gold farming on non-Exchange servers, as players interested in buying with real money relocated to the Exchange servers from the normal servers.
They also noticed that it didn't really stop gold farming on the Exchange servers, many still worked outside of the established system they'd put in place.
And finally, it wasn't really that profitable.
No hard facts, but I think a dual currency system would be better if you must have a system that supports real world purchases.
I don't think anything should be done considering the devs/pubs of these games are unwilling to ban gold buyers. Given their access to game data and metrics the companies that run the games should be able to quite easily pinpoint who is buying gold and perma-ban those accounts. If they banned enough buyers the sellers would disappear as well. Since the companies are not willing to do this I see no need to take extra steps to inact drastic changes to games to fix something they clearly don't want to fix.
Seems like Blizzard had the same idea that I had. http://us.blizzard.com/en-us/company/events/diablo3-announcement/index.html#auction:auction-summary I wonder how well that will work out, and if it's successful, will it spread to other games?
I can not remember winning or losing a single debate on the internet.