Just because he made three poor Star Wars films and produced one terrible Indy film doesn't mean his mental state has deteriorated.|
I think the simple fact is that there's mountains of money to be made from this deal from all parties.
What is good about this is that Lucas is no longer 'master and commander'. That means that in theory Disney could hire the best talent out there to make the new films.
Hell, they could even hire Spielberg to make one.
The Resident Evil films. I'm one of the reasons they keep making them.