LED1.write(1); save(); didn't save LED1 state after power off. why?

This is expected behaviour. If you want to force LED1 on at startup, do:

function onInit() {
  LED1.write(1);
}
save();

I'd been considering saving pin state, but I'm not sure if it's such a good idea as often connected devices will actually need more complex initialisation done to them than just setting pin state back exactly as it was. I think very often it's actually better to force people to explicitly set the pin state.

I'd be interested to hear what everyone thinks though.