Yet another example of this (though handled somewhat more smartly) might be TOS: "A Taste of Armageddon". (We're really picking on TOS, aren't we?) Here the writers chose to go after not just that old Left Coast favorite, "War Is Always Bad," but to unleash personal commentary on the policy of resisting the spread of Communism in southeast Asia as well.
As noted at Memory Alpha:
According to David Gerrold, the computer tallies of war dead in this episode was a statement about Vietnam War deaths that began to be registered on nightly newscasts in 1967.This, at least, seems marginally more subtle than the message in "Let That Be Your Last Battlefield," but it probably didn't seem subtle at all to Star Trek viewers living in 1967.
Again: Getting some viewers of a TV show riled up by portraying their beliefs as stupid or evil (under the cloak of "it's just entertainment") is one thing. Doing that to people in a massively multiplayer and highly interactive game is another.
I'm not unalterably opposed to challenging people's beliefs in a MMORPG, but the fact that it's a game, and that it's an environment where anonymous people can affect each other, means that such moments had best be extremely rare and handled with great fairness and respect for diversity of opinion. It's possible that some game development company could do that well...
...but is it wise to bet the game on that?