Practically the entire audio field(recording, synthesis, processing, sequencing, etc.) has stayed away from Android because latency is far too high on average, ruining UX; it also varies widely between manufacturers, which doesn't help matters.
To some extent this also impacts all games, since high-latency playback hurts the experience.
I am wondering how true this is with Android 4.1+, because audio latency was one of the major goals for Android 4.1 and more so in 4.2 and was supposed to bring audio latency on par with iOS.
edit: So, even when said apps were not possible in the past, now would be a very good time to port your app (or those apps in general), because then this is a niche which is not yet filled and there is some money to be made by being #1 in that niche :)
There's some hope for 4.2 but needless to say there's no point targeting that market yet. None of the devices currently on the market have acceptable audio latency. And Android still has no MIDI support.
Android has its strengths but it can't hold a candle to iOS for these kinds of applications.
Mh, i just tested on my phone ( https://play.google.com/store/apps/details?id=de.darkbloodst... ) and i don't see/hear a latency, certainly nothing above 100ms, so i don't think your remake "NONE of the devices currently on the market.." is true. My Galaxy Nexus is over a year old and works fine. Atleast i suppose that this app would show what you think is not working.
Latency for pro audio apps should be around 10ms. No Android phone gets close to this but all iOS devices do. You can use the free Caustic app on Android to measure your exact audio latency and then you will understand why none of the pro audio app makers bother with Android despite the large install base.
To some extent this also impacts all games, since high-latency playback hurts the experience.