Why do you allow your forum users to tell your other paying customers, "If you don't like it, go play GameX instead," whenever another player complains about a feature (whether the complaint is justified or not)? Do you really think Blizzard needs that $15/month more than you do? Is it your intent to allow your more rude players to send paying customers onto other MMOs, until all that's left are fanboys who lick your boots and tell you how great you are? Because I promise you, it's hard to make rent and pay server fees with only a few hundred players paying you $15/month.
The rudest gaming forums I consistently come across are those for MMOs, and the more niche the game, the more rude the forum users. Suggestions that might make the game less confusing are met with diatribes about lazy gamers wanting an "I win" button. Comparing the MMO with another are met with sneers and the aforementioned demand the customer take their money elsewhere. Complaints about bugs are met with, "Quit QQing. It's not affecting gameplay."
Here's a shocking revelation: MMOs require customers. They require a minimum number of customers at that, assuming you want to pay your programmers and content designers and network administrators, not to mention making your rent and electricity.
Stop allowing the bullies to dominate your boards. Insist on a certain measure of respect among your players. Not every player is going to /ragequit when they get fed up. Sometimes, they'll simply unsubscribe.