BTW, what about UDF? Apparently it should be supported by Windows at least and should handle big filesystem sizes just fine.
Why is nobody speaking about the obvious solution? exfat support should be a paid "app" and cost exactly what it costs to license it from microsoft and it should say so in the app description. It could also be an "upgrade" for $XX that you select when buying the device. I don't care about making an account there, but the reply to "If you want this to end educate your friends/relatives/whatever" should be to make a pop up: They will just plugin their sd card and get a pop up: "Want to use this sd card with exfat? Microsoft requires you to buy an exfat license for $XX to do that" and then allow them to easily buy such a license.