People that think this is unacceptable are not remotely average users. Average users benefit greatly from their pocket appliance not being a full fledged computer.
Fundamentally, it is a trust issue. Why should I be forced to trust Google or Apple has my best interests in mind (they don't)? That is not ensuring 'device integrity', it's ensuring that I am at the whims of a corporation which doesn't care about me and will leverage what it can to extract as much blood as it can from me. You can ensure 'device integrity' without putting any permanent trust in Google or Apple.
You are not.
It's certainly convenient in this modern world to pay for and use one of their devices though.
Limitations because it's not just protection - you don't get to choose which authorities you trust. Defaulting to manufacturer/OS vendor as the default authority would be ok, but there is no option to choose. Users have no power over their own device. That's not ok even if most choose to never execute it or don't know about it, it will lead to abuse of power.