Eh, not so sure that's "enabling" - it has always sounded like they realized what a mess it was story-wise and didn't want to be responsible.
If you read the Rinzler making-of books (incredible, I can't believe they let him write them they are so honest), you see that each script for the OT was worked out over many months in story sessions with multiple people and the end results were remarkably different from the first draft.
For the PT, Lucas literally locked himself into his office, came out with a draft, and said "ok this is what we are filming". Except for a few dialogue contributions from Carrie Fisher (some lipstick for the Hutt), that was really it. And that's why the films are so disjointed, because he wrote the scripts one at a time right before filming each one (even he admits he wasted too much time idling in TPM so he had to cram what really should have been in multiple films into ROTS).
When you really read the day-to-day history in the Rinzler books, it becomes very clear that while George Lucas had the vision, just about everything that was most successful in bringing that vision to life was due to the contributions of other people. There is a reason Marcia Lucas won an editing Oscar, Brian DePalma worked on the opening scroll and sat in on all the casting sessions, Kasdan formed the ESB script...he had the vision, but like a lot of geniuses, they need other folks to help them clarify and make sense of it for it to work.