Yes this is exctly what I'd like to see, an appliance protocol of some kind. People can then write their own apps if they want. Maybe just REST endpoints -I've seen web servers of sorts crammed into avr chips, so it should be feasible with all but the most limited devices.

App rot is a problem no doubt but do apps break quicker than the crappy hardware UI? I'm not so sure. probablty on iOS that's true.