Because we feel like we can offer better service by specialising, since we can test the apps ourselves, etc. We want to give every app a considerable amount of attention so the final result isn't just a translation that "makes sense," but that will be truly appreciated by users in Japan.
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.
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.
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.
