Keep in mind that many of the people mentioned above either think that the Magisters are truly there to help them or seem indifferent to the situation.
It's also worthy of note that the most potent aspects of their force are things we see but don't interact with directly. It's made pretty obvious in the game that there are two parts of the Magisters. The low level grunts that are pretty much just a cover and the people who know what's really going on that tend to be much more powerful.
As a side note, while I don't remember specific instances of this in game, there could easily be a bit of guilt in play for the sorcerers in question who may have, even without trying, been causing the world to decay. The truth of the matter may or may not be that but if they believe it then that is what they would act upon.
