Closing the side loading option is a path to antitrust suits, a slap in the face to privacy, a kick in the teeth to independent devs and personal use.
There is zero reason for this other than wanting full control of how I use my own phone and how much money/data google can squeeze out of everyone.
I did not purchase a phone to have it later be functionally broken as features it had have been stripped in the name of 'security'.
A warning message is all that is needed. The current toggle is enough.
We are not toddlers.
There are not possibly enough cases that it warrants such a restrictive policy aside from the stated reasons above.
Give me liberty or give me symbian.
How's that?