Another often overlooked pro to short stories is that they adept quite well to film. The criticism most often made about movies based on novels is that the movie changed the book. The eloquent descriptions and beautiful detail that make a book memorable usually have to be cut out or changed in order to translate to a two hour on-screen event. Interesting sub-plots become an optional luxury.
But short stories thrive on the imagination. The best ones merely create framework so as to let the reader fill in the blanks. This works especially well when translated to the screen. The director and script writer are completely free to provide their own interpretation of the story. This very same freedom has led to some of the most memorable films of all time:
It's a Wonderful Life
Breakfast at Tiffany's
The Day the Earth Stood Still
3:10 to Yuma (1957 version)
You can read a more complete list here.