I can't honestly answer the question, because it's complicated. Roddenberry left for Season 3 of TOS, and the quality was lacking. Then, after several attempts to get another series off the ground, he gave us THE MOTION PICTURE. The story, while re-hashed from a TOS script, was clever, just boring and effects heavy.The best thing the did was put him in a consultant position and allow others to make STAR TREK, which gave us THE WRATH OF KHAN. Roddenberry had control again when he created THE NEXT GENERATION, and it was a great show, but again, writers have gone on record as saying that there were some really great storylines that they were able to write only after Gene had passed away. I think he was a hindrance to the franchise.
I see Gene and George Lucas as being very similar. They had some success with other projects, but then hit it big with one cult project (STAR TREK and STAR WARS, respectively). Both had great vision, and had some help making it great. But eventually, whether it was a matter of them believing their hype or just plain hubris, they thought they knew what made their creations great when they really had lost sight of what it was that made people fall in love with them.