For me, the short story has always been the champion when it comes to the telling of certain types of stories. It just feels that they fit the format so much better than they do in a longer form such as novelization. Horror first comes to mind, second is my love, the ‘steampunk’. (If you didn’t know this, then perhaps you’ve come to the wrong author…)
The short story format can also help build relationships with other authors and related content creators by the use of the ‘anthology’. The modern anthology is a neat way to get writers to contribute to the same topic of writing. You can invite others, or use edited contributions. The internet has also greatly reduced this barrier by enabling authors who are separated by impossible geographic areas to contribute to different anthologies. Short story formats usually work best with at least a couple anthologies that use longer methods.
In summation, I just wanted to say that for me as a writer the short story will also be dear to my heart. If you can site down and bang out novel after novel after novel then I will not rain on your parade, go forth and do so! But I would personally rather curl up on a cold day with a nice short story. Happy writing!