I think the idea is choice. A device maker could make a dumbed down version for mom and a power user version for you. The iPhone is somewhere inbetween.
Who says the mom would be setting up the device? It would be easy enough for your cell phone carrier to setup and customize their own interface/variant of Android phone.
A touchscreen Jitterbug phone based on Android would be pretty cool. You can make even bigger buttons, text and UI elements than the current model and eliminate almost all unnecessary functions.
Give an Android phone to your mother and see how often she calls for help (if she can figure out how!)