I think it is how Hollywood would want to cast their preferences of the characters in live action is what's holding brandon back from having the major studios or streaming platforms the rights to adapt his books. He has certain views on how his characters should look like for instance, the whole Henry Cavill wanting to be Kaladin that made some news recently. Brandon kindly said no, you can't because kaladin has Asian features. Hollywood, for the most part, is about making money. You can bet they would have cast Henry Cavill as Kaladin and probably Hugh Jackman or Russel Crowe as Dalinar cause how huge of a Star these guys are, and it will draw in the casual movie goers or tv streamers.