If I were teaching History of the Cinema, I would teach to those who appreciate the cinema. A group that has passion for the cinema and who sees it as an art form not just entertainment--specifically, aspiring filmmakers. Just like most career fields, studying the history of those fields is not only healthy but also vital for workers best understanding.
Could someone be President of the U.S. yet know nothing of politics? Could Babe Ruth have made an impact on baseball without ever learning how to swing a bat? Or could DaVinci have painted his masterpieces before learning how to use brushes and paint? Granted, a young filmmaker could attempt film without any historical knowledge. It would most likely be a disaster--an unholy mess that would not be taken seriously.
Film makers need to see the great cinematic achievements of the past. They need to study the storied careers of famous, and even the infamous legends of film, both onscreen and off. They need to see what has been done, who did it, why and when they did it. They need to know the unlimited potential of film. They need to be educated and inspired by the gems of film.
I would show the films that have the most impact: Citizen Kane, Birth of a Nation, Psycho, Casablanca, Gone with the Wind, The Wizard of Oz, Monty Python and the Holy Grail, etc. These are the films that people cannot stop talking about--the films that stand the test of time.