It is also assumed that George Lucas thought to himself after Raiders had come out that people weren't interested in the story, all they wanted was the spectacle.
George thought that people just wanted the roller coaster ride and weren't all that worried about the writing.
I guess he just never assumed that movies should have to worry about replay value.
He's even said that he knew the special effects in the original STAR WARS wouldn't stand up to repeat viewings.
Once again, he's not worried about replay value.