I wrote my first short story for the simple reason that I'd read it was a good idea to gain some publishing credits in order to grab the attention of an agent. The logic--if you can prove you're publishable on a small scale, then you are likely publishable on a bigger scale.
Something odd happened, though. I really enjoyed the writing! It's a different process than novel writing, for sure, but it's quite fun. I thought I'd list a few reasons I love short story writing:
1) Time. Obviously, it takes less time to write a short story than a novel. That includes critique and editing. Which means, I can get it submitted right away, and, in turn, get it published rather quickly, too.
2) Learning. Short story writing has taught me how to write concisely. When you have to get an entire story out in a few thousand words, you can't put in anything unnecessary. It has also taught me how to start the story in the right place, for the same reason.
3) Easier submission process. The submission process for a novel is long and tedious. You have to write query letters, synopses, and wait forever for responses. The submission process for short stories involves a short-and-to-the-point cover letter. You then attach the story and go. Often, you get a response in a matter of weeks, or even in certain cases, days.
4) Connections. I've made some real friends writing magazines--both the editors of those zines and other writers who also have stories there.
5) Exposure. My name is out there now. Readers who love my short stories will likely recognize my name when my novel(s) come out some day.
6) Less pressure. I can be wildly creative and not have to worry about investing too much in a story that doesn't fly. It's not like writing a novel and half-way through realizing it's not working. If a short story doesn't come together right away, it's easy to scrap it and move to the next one. I can try all those weird ideas I'd be too scared to base a novel on.
7) Variety. So many story ideas! So many settings! So many characters! I don't get stuck in one world with one set of characters.
8) A bigger novel world. I've written quite a few short stories based on my novel. I get to write about things that aren't directly related to the story in my novel, but enrich the world of it.
9) Money. Um...well, that would be one of the reasons if I actually got any! Seriously, there is potential to earn money on short stories, but paying markets are few and far between. I've got several token payments, and one $50 cash prize. I am, however, hoping that one day money for my short stories will be a regular thing. (Keep in mind, I'm talking fiction here. Nonfiction almost always pays.)
10) Reinforcement. I may have given up on my novel-writing by now if I didn't have the "proof" that I'm a good writer in the form of short story publications. When I'm having those down days, where I wonder if I'm deluding myself about being a writer, I pull out my portfolio a look at what I have accomplished. That may sound like ego-stroking, but I don't think so. I'm not arrogant about those publications--I'm grateful for them. They hold me up and keep me from giving up.
11) Cliche titles. Yep, notice the title of this post. I love using sayings and such as titles. "A Day Better Spent," "Like Stink on a Dog," and "Cat Call" are all titles I've used for short stories. You can't do that with novels--or at least you shouldn't ;).
So, there. Maybe you haven't tried short story writing and this will motivate you to do so. Or maybe you already write short stories and can attest to my reasoning. Maybe you have other reasons I didn't list here--if you do, feel free to share!