Okay, and how am I going to give the user the right to wipe all software from the device and use a completely custom software?

I mean, we all agree that such permissions are not required during everyday operations, but there should be a way for the consumer to have control over the software being used. And I mean all aspects of the software: firmware should be updatable, the OS should be replaceable, and the security concepts within the OS should be customizable by the user as well. I have no problem with hiding such functionality and requiring users to read the documentation to find out how it can be done, but it should still be possible.

Sure, but such a product requirement can be made to be legally required without legally requiring root access.