Movie Ticket Inflation...
This is interesting stuff ... My guesses as to why would involved the fact that Hollywood can't seem to make a movie anymore under 2 hours to save its life. For example, The Hobbit was almost 3 hours and it just got to roughly page 105 of the original novel. in comparison, most of the original Chaplin films were under 80 minutes. Many films in the 1930's era were an hour at most.