Part of the Godfather was that it played on a lot of popular themes and styles of the time. I forget where I read that but I know that these kinds of slow burn french inspired but low dialogue thrillers were much more common then. I think its best to understand these movies as both historically important, and being the best of their time, or of a certain genre or style. I think of sports the same way. People endlessly argue over whether its Ruth, Bonds, or Mays but really each of the three was the best of their own era. Ruth is the most dominant player of all time, Bonds is the most dominant of the modern era, and Mays is the most complete player of all time.