That's a fair point; though I am not sure what limits you from testing on other platforms. Even if you don't have real hardware for them, most of them have cross-platform emulators.

They're doing it for free. They have a right to be picky :)

Damn right! They have a right to be picky if they're charging too :)

In that regards, it's mostly a matter of simplicity. It's easier for us to work with the devices we have (and love) and to market based on a specific target.

Because its less fun if you can't see the results.

And fun is important when you're doing something for free.

That still doesn't explain, for instance, cutting out translating web applications or PC/Mac software.

You should be specializing in translation, regardless of the format you work for. And I'm pretty sure you can find a cheap Android phone around to test if things work right.

My partner already does "specialise" in translation. She does freelancing for a living. I simply had the theory that it'd be more effective to niche down, and I chose to target iOS because: I'm a user of iOS, I have some iOS development experience, and the App Store is growing in Japan. We're not basing our livelihoods on the decision. It's just something we're testing.