My guess, it's because of the same reason why there are more and more haters a few months after Diablo3 was launched:
High expectation + low replayability is how the first wave of disappointment hits;
For each update, more and more people start to pick bones from the egg, and surprisingly they actually found one piece of bone or two or even more;
Some start to share those little pieces bones on internet, and some start to look for more bones found by others on internet. Even without realising that these bones were not the reason caused their disappointment in the first place;
Then some went silence, some started to troll;
Thus the hate remains.
It's a loop that repeats itself everytime a new update was released. I'm happy that TW finnally slow down the update rate btw.