From the LA Times:
But 1980 was also the year that Kurtz and Lucas realized the Jedi universe wasn’t big enough for the both of them.
“I could see where things were headed,” Kurtz said. “The toy business began to drive the [Lucasfilm] empire. It’s a shame. They make three times as much on toys as they do on films. It’s natural to make decisions that protect the toy business, but that’s not the best thing for making quality films.”
He added: “The first film and ‘Empire’ were about story and character, but I could see that George’s priorities were changing.”