Well, I disagree.

If he really feels that way he shouldn't have come back at all. Star Wars has a legacy now, compared to when he was cast. There are things you have to be a part of when you sign on, the newcomers understand this. Is it written anywhere? No, but look at the others like Hamill and Fisher, they understand how much it means to people. There's an entire convention around Star Wars.

My rule of thumb is if you're not passionate about it, you shouldn't be involved.

Steve Jobs felt similarly, and would fire people who were really skilled and good at their jobs because they didn't care about Apple's vision.