He never understood software freedom, but as far as I can tell he is responsible for communicating the way that free (as in freedom) software can be competitive in the real world. Before that, all anyone would talk about was how we had to have free software for moral reasons (which I personally believe). He was the one that saw how successful projects were being run, put 2 and 2 together and told everybody else how to do it. I have much respect for ESR and I wish that the good things he has done had a wider audience.
Unlike in fiction, real-life humans aren't universally perfect to everyone's standards. In some areas they believe or practice something great, in others they say or do repugnant stuff. Fortunately, you can evaluate one's contribution in different areas in isolation, and I wish more people would learn how to do that.
Most of his open source contributions seem to be littering up source files with long-winded comments and grandiose attributions to himself. I've read a fair bit of his code and it's certainly not impressive. Quite the opposite actually.
Richard M Stallman.