See the big wall of text by @Alcyon_Densetsu Mostly agree with that. Typically when people have a problem, real or imaginary, they want to complain. Sometimes you have that amazing moment you feel you just have to share, but those are less common. Usually it is more along the lines of "hey that was awesome", and you move on. Negative things on the other hand just get bottled up until you feel you have to share.

Thus the people most likely to post are the ones who have something to complain about. This in turn attracts the reverse complainers and die hard white knight: the person who looks for slights where there are none, and looks for a reason to attack the poster or defend the product. This means the biggest most active threads are going to be negative by nature. Then you have the first group @Alcyon_Densetsu talks about, and they dive in to the negative posts, to try and help diffuse things which rarely works, and makes it seem like everyone on the forums is involved in the negativity.

You also will note that most of the negative posts get comments by the same people, if they weren't started by the same people. If you do the math, there are less than 1% of the total player base who are active in the negativity the forums.

Mind you there are also valid complaint threads, constructive criticisms, thoughts on improving the game, but these usually get run over by the negativity groups, either to defend the game, or generally hijack to vent something else. I think everyone has probably seen this, if not been guilty of it themselves at one point. Negativity can be catching.

The best bet is to try and retain objectivity as much as you can, and if you dive in, be rational and have a coherent reason for why you are involving yourself. Otherwise, only post on the positive, or silly, or innocent question threads. (Which so often get buried before they are even seen).