Kyoda and Sato pretty much both came up with the concept/story of the show as you see it on screen. Obviously people like Kawamori, Yoshida, etc, informed decisions along the way, but the final product is as much Kyoda as it is Sato. Even the music/cultural influences, which people would most likely credit 100% to Sato...Kyoda was just as much responsible for that aspect of the show. The only difference is that Sato considered the ending of the show definitive and did not feel it was necessary to revisit it as he accomplished what he set out to do. Kyoda obviously felt (still feels?) differently.
And its not just Kyoda who wasn't able to move on, just have to look at Masayuki Miyaji and Xam'd. He obviously wasn't able to let go in his own way either.