The road to monetization is often a bumpy one, especially when you have a large established base of players used to one business model and you try to introduce a different business model. Such is happening right now with EVE Online, the quirky MMO with the dedicated fan base that's been making money the old fashioned way, via subscriptions. Lately they've introduced an in-game store, and that's when the rioting began.
Yes, rioting. It's complicated... but EVE's in-game economy is connected to the real-world economy, in that you can buy sell things for cash. And EVE players are worried that the new store items may completely unbalance the economy. (I guess Iceland is already familiar with economic upheaval, so why should this be a surprise? The developers of EVE are Icelandic, and Iceland's economy went into a tailspin a few years ago when bank failures occurred... but that's all in a different universe than the game. Sort of.)
Players are outraged over the high prices for some of the items in the store... real-world costs for in-game items that exceed the real-world costs for the same item. Worse, some of these vanity items cost more than major capital ships do... more than $60 for a hat, for instance. Players seem concerned that this will lead to the guy with the biggest spending being the most successful in the game, buying their way to victory.
The problem was made worse by an internal memo that was leaked, where the company envisions players buying ships, guns and other game-affecting items. CCP, the developers, have been trying to calm the waters, but so far it's about as calm as Syria is right now.
Lesson: People take games seriously, especially one where they spend hundreds of hours playing. If you introduce new ideas that threaten to invalidate their hundreds of hours invested in the game, outrage results. Tread carefully when mucking about with game balance.
There's a lot to be said for the League of Legends philosophy: Don't sell anything that can affect the game play. You may miss some revenue right away, but you'll also avoid riots.