But science fiction has a greater impact in being one of the few forms in 20th century arts that dared to present an optimistic view of the future and of values that led to a better world, be it Picard's exemplary leadership in Star Trek TNG, or Heinlein's "normal person finding their courage and values has an impact" novels.
Apocalypse Now or Brazil may be "great" movies but they are incredibly depressing. "Resign yourself to the brokenness of the world, people. The state/realpolitik will crush you." "No", says Asimov, "your actions matter and have an impact. Courage and reason are great qualities, go build the world you want." How many other mainstream movies, books or artworks have this message, outside of science fiction?