"Companies should just stop gold farmers." It's a consistent complaint in many games, with "gold" replaced by your game's currency of choice. As complaints go, it's right around "somebody should do something about all the problems" in terms of overall utility, but heck, no one likes the practice and it should just be eliminated, right? Well, as Scott Jennings has pointed out recently, it's not quite that easy.
As Lum points out, there are several common misconceptions about the entire process. Among them are the idea that the game company doesn't step in because they're getting kickbacks, which is pointed out to fail the simple test of Occam's razor. When developers want to get more money from an existing game, there are usually better ways to run it, such as the Champions Online model or the Dungeons and Dragons Online approach. He also tackles the infamous statement that the farmers are paying customers and therefore the company has even less incentive to stop them.
So if everyone hates RMT, why is it still around? The article briefly touches upon it, but We Fly Spitfires had a recent post that articulates more specifically: more people buy gold than would necessarily admit it. Since no one will admit to it, no one ever asks, and as a result there's a large culture of silence that publicly despises it and privately takes part. In short? As long as there's a customer base, the farming will continue. Food for thought all around.