Directors or actors/actresses who "didn't get it"

some would argue both George Lucas and Gene Roddenberry

Starting with the Motion Picture Roddenberry was basically given a ceremonial title and role and others were tasked with keeping him away and his involvement/interference to a minimum (for all the original cast movies he kept pushing a time travel movie where Kirk would have to be the one to assassinate JFK in order to preserve the timeline (basically a big budget, big screen update of City on the Edge of Forever)

Starting with the prequels people have accused Lucas of not really understanding Star Wars or why people loved it, but even a large part of the original trilogy was due to his then wife Marcia

And I've heard people say Return of the Jedi was when his focus became more about selling toys than creating a great movie