A lot of the people disagreeing with my concept of social responsibility used various forms of an argument which basically is: "Who are you to tell us what is wrong or right?". And that is a very good question. What makes me think that I can claim that there is a social responsibility to sometimes play a class or role which is needed instead of saying "It's just a game, I want to play DPS, and nobody can tell me to play something I don't choose"? Fortunately the question of what is right and wrong has been extensively discussed by clever people hundreds of years ago. And one very good test was proposed by the philosopher Immanuel Kant. It is called the categorical imperative, and invites you to simply think what would happen if everybody acted exactly like you. If that leads to a situation that would work nicely, the act is good. If everybody acting like you would lead to a collapse, the act is wrong.
So lets apply this test to the DPS situation: If everybody in World of Warcraft would play only DPS classes or roles, and refuse under any circumstances to switch to a healer or tank role, what would happen? To me it appears obvious that this would lead to World of Warcraft being effectively only playable as a solo game and in PvP. Dungeons would have to wait until people would have sufficient PvP gear to so completely outgear them that they could be done with 5 DPS. And to do a raid you'd need to go back to one of a previous expansion.
The position to play only DPS and refuse to ever play another role only works because *other* people are willing to tank and heal. That is what Kant would consider morally wrong, with the argument being that if you are unwilling to do something, you shouldn't oblige somebody else to do it in your stead. And just counting on the people who really *like* to play tanks and healers doesn't work either, because obviously there aren't enough of them around, or we wouldn't have the problem and the discussion in the first place.