I understand what you mean. Although I am not quite sure why a program that asks for Wifi name and password should be easier to handle for the average joe then clicking the wifi button on a OS and typing in the password which is a lot close to what they are know from their Windows system and do not have to understand another UI they need only for the first Setup.
Well however when you really want to do this for the average joe so he has absolutely NOTHING to do with anything but their favourite spysystem windows ;) I would write a windows tool for it. Either one doing it over SSH (which I do not really like because the average joe will just leave SSH open with standard key and you have to explain them what the heck is SSH and how to activate it) or just let the user plugin their SD card which they have to do anyways when installing Linux and let the program edit the file including all Wifi logins. For the rest of MM2 you could do a preset Image of debian that already has MM2 setup (maybe create a auto update tool for debian that just checks for OS and MM2 updates once a day