Yeah, his main motivation was pride and delusions of gradure. In case you didn't notice, his motives weren't pure, not even from the start, he was quite clear about wanting to be a god.
Besides, whether his intentions were good or not, his actions are the problem. He killed people. LOTS of people. It doesn't matter if he decreased crime, he was a murderer. Hey, guess what? If you killed everyone in the world, there'd be no more misery. His whole plan was based on the idea that the end justifies the means, and it never does.