When I was in my senior year at university (1978) I took a class in dramatic structure, and one of my classmates had somehow gotten hold of a copy of the Star Wars (what we now call A New Hope) shooting script. The instructor (head of the drama department) immediately latched onto it as an example of a screenplay, while all the other reading was plays. George Lucas may not be a great writer, but the Hero's Journey structure of the story made a great study for the class.