The argument for this approach is that it narrows my subject choice significantly. The limitations may force more creativity and I might end up with a story I never would have written otherwise.
The argument against this approach is that sometimes I'm stuck with a theme that doesn't inspire me. I know it's usually recommended to want to write a voluntary submission, but I'm forcing myself because this is a challenge.
Can I make myself care (and ultimately a discerning reader) about something that's never interested me?
The prevailing wisdom for writers is that you can't wait to do your job until inspiration hits. You just have to do it everyday, no matter what. So the real question becomes: Can I produce a good story without waiting for inspiration?
The theme I'm working with is a big one. I figure it's my own damn fault if I can't see anything interesting lurking at the edges.
In the future I'm sure I'll choose my projects more carefully, but right now this is a great exercise. After a month of false starts I've finally found a story I can write. Now I just have to figure out how to tell it.
You know, the easy part.