I agree Lucas isnt the savior and he does need someone to bounce ideas off of but I honestly think thats true of any creative endeavor, especially as the medium becomes more complex. Tolkien got some support from CS Lewis while mapping out Middle Earth for Lord of the Rings. Manga is often created as a team of at least 2 people (one to write the story and dialogue and one to draw). TV has a team of writers, let alone the rest of the production staff. Movies even more so.
I think Lucas knew that himself, hence why the first thing he did when making PT was to reach out to veteran directors like Howard or Spielberg to direct. They unfortunately turned him down.
If Disney had a brain, they would have still used Lucas as a consultant. It's his universe and I think with the Sequels there needed to be an adult in the room to look at what they were doing, before filming, and go "No that's not SW." I think that's why most of the designs, from vehicles to characters to locations were so bad. If you've ever watched or read an interview with the concept artists, they always said Lucas would look at their designs and sometimes veto them, tell them what to change to make it SW, or flip things around to make them look like SW. That was missing in the Sequels.