My take on this is that T20 is a batsmen's game. In the shortest format, people want to see boundaries and sixes. That is one of the major reason people buy tickets and come to the stadium. Having a score of 100 odd won't do any good and won't qualify as entertainment. As unfair as it may sound for the bowlers, in this format the public prefers seeing the batsmen hit sixes rather than the bowlers taking control of the game. It's as simple as that.
So it comes as no surprise that a "difficult" pitch will always be looked down upon in T20s. The case is, however, reversed if the format is Test. That's the beauty of it.