The packaging system is only a part of puzzle. I can control what happens with my Linux laptop, but it's much harder when 10+ devices around you are constantly updating. There's also the thrust issue - we all want exploit patches to be applied automatically while feature changes are different thing altogether (remember when Sony pushed update to PS3 that disabled OtherOS support).

Maybe a good legal solution would be to allow automatic updates, but only if user is informed about changes and she can downgrade/revert at any time. Also, the stuff that Microsoft does with Win 8/10 upgrading should be punishable.