What's there currently is the result of learning the hard way that unified keymaps for anything more than the simple "4 directions + action + quit" doesn't work on the vastly different key layouts with their electrical, mechanical and physical restrictions or possibilities.
There was a more complicated (and "global") system before and even though only a few plugins were using it, some of them had broken controls on some targets. So we went back to saying "ok, if a plugin uses the simple scheme then it can use the simple global system - if not it shall define its own".
I rather have a bit more inconvenience for the one time a new port appears than non-working controls and always having in mind that a fix for one target may break another.
Out of curiosity - what did you prepare for the android devices? I would think that there already is something generic for "touchscreen" - and then there is a ton of different key layouts for different android phones ...