Correct me if I'm wrong, but weren't there plenty of "message" movies that came out before 1963??? Frank Capra's films of the 1930s and early 1940s immediately come to mind. So do Stanley Kramer's films of the 1950s and 1960s. And what about "High Noon"? While this list is more than incomplete, these were just a few glaring exceptions to your thesis that I came up with off the top of my head. While they were aimed mainly towards a broad audience and did emphasize "story", their messages still came through quite dramatically and were definitely intrinsic to the film's appeal. Just a thought.