Using the Apple example again: How would an non-techy react if on one iPad the switch locked orientation and on another it muted the device? Where would they find the setting? Would they even think to themselves that a setting must exist?

This is the reason the option was changed to mute - to match the iPhone. IMO, the devices are different enough where I think it could have been left the way it was however. I do think there should not be a setting to modify the hardware button though.