George’s worst decision (or perhaps more accurately his biggest mistake) was allowing himself to get sucked into the merchandising machine. Most of the problems people have with the franchise as a whole can be traced back to this.
The development of RoTJ was basically entirely shaped by the toy companies; both Gary Kurtz and David Prowse have confirmed this independently. Rather than focusing on crafting a satisfying dramatic conclusion to the trilogy, the final chapter became little more than a glorified toy advert in George’s eyes.
I find this toy selling conspiracy with regards to ROTJ ridiculous. They sold just as much toys for ANH and ESB as they did for ROTJ. People try to point at Ewoks as the main “evidence”, but the fact is that difficulty of getting so many that tall people to play Wookiees (originally intended) is way more reasonable explanation.
It also does not have much weight coming from Kurtz (who was being fired during ESB for incompetence and had nothing to do with ROTJ) and Prowse (who seemed to have be acting as jerk for years before he eventually got banned from LF events).