In response to a suggestion to "poll" class changes from players, Moorgard goes into a fairly lengthy description of how classes are viewed, and how developers make changes.

While customer feedback is crucial in MMO development, there must still be a line between player and developer. While players tend to know certain aspects of gameplay extremely well--in certain cases, better than some devs do--developers almost always have a broader sense of the game as a whole. If they don't, they tend not to be developers very long.

You can find the rest of his post here.