Actually what he did right with Pixar was to let the creative people be creative. I realize that sounds like nothing, and yes it is nothing -- but it's everything and here's why:

A bad producer or studio head who isn't a creative will always get his or her paws all over the film projects and tend to ruin them. Or worse yet select projects not on the creative merits but on a perceived notion of how they'll do in the box office -- the result is all of the bad special effects and franchise movies we see today.

Instead Steve had the rare courage to do NOTHING except let the creative people "make a great film". That's something that's very rare in Hollywood and deserves a ton of credit...