I thought it also sent a clear message that someone like Ramza could never change anything for the better. Sure he stopped the Lucavi, but that was preventing a change for the worst. What I got of it was that they needed a hero like Delita to be willing to get his hands dirty and change things for the better.

Death Corps and Delita are completely different examples. Death Corps, like Ramza, tried to change things from outside the system. They were overwhelmed and killed, much like Ramza would have been should he have taken a stand and actually tried to seize any sort of power. Delita has the intelligence to realize that fighting the system from the outside serves nothing but making you feel self righteous. He was more concerned with the future of Ivalice than feeling like a hero.

Also, I don't really think a whole lot of people were even pretending to be acting with the people's best interests in mind. For a noble that isn't even considered an un-ethical act. Their actions were considered completely justified by the morals of the time.