I've never been especially good at writing short fiction, because my ideas tend towards expansive. The smaller ideas, which might take less time to articulate, usually end up getting folded into one of my larger ideas in order to enhance it.
I recently finished a short story that was originally intended for that very fate. It sprung into my mind, then I reworked the idea to be a scene in a novel, and now I've taken it back to stand-alone short status. First draft ended up pretty well, and now it goes into its metaphorical drawer for a few weeks before I edit it.
I'm already wondering what else I could include, or what bits might be expanded on. It is very short, about a thousand words. However it is also tight, and probably doesn't need anything beyond the scope of the story itself expanded on. Better to let readers wonder. Still, my urge is to tell more, write more, give more. Another reason I'm not so good at short fiction. I don't necessarily like leaving so many mysteries, or details, unresolved.
On the other hand, it is always fun to finish a story, and shorts give a little "shot" of that feeling. A friend of mine also raised the fact that yesterday's short story can become tomorrow's novel.
On a somewhat related note, my (free) released short story "Le Morte d'Arthur" has seen some additional success, cracking the top 25 Ghost stories on the Kindle boards. It seems the rapid increase in downloads coincided with the story garnering its first review. Correlation != causation, but I can't help but suspect the former influenced the latter.