Short films are the platform used to launch the careers of many aspiring and talented artists like Christopher Nolan, who try but fail to make the big screen debut early on.
These films have content that is often far superior to the big billion budget films due to their compact running time, which forces directors to be creative. They must quickly captivate and engage their audience in a story that begins and ends in thirty minutes or less. Many short films fail to do this, which may be why most of them never see the light of day in a theater.
But not all short films fade into obscurity. Some are picked up by large, well-known studios and showcased in theaters or on TV. Tim Burton's 1984 "Frankenweenie", originally commissioned and then rejected by Disney, was brought to the light of the public by Paul Reubens, who had been told about the film by Stephen King. This short film not only launched Tim Burton's career, but became famous in its own right, and it even received a full-length remake in 2007 in celebration of the film's legacy.
To say that short films are not worth watching because they never enter theaters is not only inaccurate, but absurd. Plenty of short films make it into the limelight in one way or another, and plenty are masterpieces which become famous for good reason.