Essentially everything bad about Lynch’s Dune is a direct result of studio mandates to condense the story into a 136-minute runtime. Except for the depiction of the baron. That’s 100% Lynch’s fault.
Backing up to this for a minute, I think that even as a 4 hour movie Lynch’s effort would have fallen short. The reason for this is because the movie seems incapable of doing more than one thing with each scene - characters enter a room, spout exposition about X thing (often with mental narration), then leave.
Take for example gom jabbar. In the book, Paul is tested to see if he is ‘truly human’, but he sees through the Reverend Mother’s facade to understand that the Bene Gesserit’s primary goal is not such tests but rather political power. He then becomes mistrustful of their order. In the movie he apparently approves of the reasoning behind the test and doesn’t inquire further as to their true intentions. Yet in the final scene of the movie he acts as if the Bene Gesserit is an enemy, without the setup from the book.
And this is just one example. Such things happen constantly, always taking a surface reading of a scene and treating it as if it were the entire purpose the scene. The Voice is now just a magical power rather than an understanding of which words will command specific personality types. The Sadukar are now just faceless brutes, and no reason is given for the Emperor’s fear of Paul beyond his power over Spice. The whole point of Dune is that every situation has wheels within wheels, and there are ways of illustrating this subconsciously or in the background without resorting to clunky exposition.