Communication with phone
My understanding is that at present 3rd-party watch app's all run on the phone with which the watch is communicating over Bluetooth. So an app that displayed a watch face would need to create the watch face graphic on the phone and transmit it to the watch every second. That would clearly be much worse for battery life (both of the watch and the phone) than a "native" watch face. Maybe this is the reason for the restriction?
Biting the hand that feeds IT
