MLK was a visionary. Roddenberry used an easily palatable tag-line to help peddle his wares and started to believe his own rhetoric late in his life.
Double this. In fact...THAT!
All of these!
On a serious note, though, I do agree with Khan444
that Gene had some good ideas. Still, his best contribution, IMO, is the Star Trek franchise. It was a good idea that hit at the right time, and worked because the casting was right (on the second try), and the writing was solid. That's what made it all work.
I tried to make a deal with the Devil, once. Turns out I didn't have anything he wanted.
You will never find a more welcome hive of love and humility.