Just stumbled across an interview of Spector talking about Epic Mickey. He says he can't take credit for Oswald or the theme. It is a shame that Famous didn't get to make that beautiful oak tree.
"I said I was interested; I'm a Disney fan from way back, I love cartoons, and it's the most recognizable icon on planet Earth. Who's stupid enough to say 'no, I'm not interested'? So I'm sitting there trying to stay cool. And then they said 'you know we have a concept. Would it be okay if we showed it to you? You don't have to use any of it.' So they showed me this pitch they had and it's genius! I mean there are some foundational elements that they came up with at Disney, that they said, 'you don't have to use it.' Why would I not? I mean, bringing Oswald back? I can't take credit for that. The idea of a world of forgotten and rejected characters? I can't take credit for that.
They threw it at me, and I was happy to catch it. So I told them 'you have just given me an acorn and I am growing it into a beautiful oak tree and everybody else who thinks they’re going to grow that tree, they got another thing coming.'"
http://www.industrygamers.com/news/playstyle-matters-warren-spector-on-disneys-epic-mickey---part-1/