DC director Christopher Nolan has said that "a real movie" would not have a post-credit scene. This was obviously casting shade at Marvel's popular post-credit trend.
Apparently, Christopher Nolan doesn't think any film prior to 1955 is a real movie.
"Casablanca Opening Titles." YouTube. Accessed November 4, 2014. https://www.youtube.com/watch?v=-pYG1Vbgq0o.
Casablanca. Directed by Michael Curtiz. Warner Bros, 1942. Film.
Franich, Darren. "Christopher Nolan Says That Quote about Post-credits Scenes Is 'inaccurate'" Entertainment Weekly. November 4, 2014. http://www.ew.com/article/2014/11/05/man-of-steel-christopher-nolan.