I'm not sure where you're getting the "legal responsibility" part from - I'm not advocating legislation, simply stating my personal preferences as a consumer. I do what I can to try and bring others to my point of view, but I am in no part trying to push this as a legal burden on manufacturers. Please don't bring strawman arguments into this, this topic is complex and nuanced enough as-is.
Regarding security, that very much depends on your threat model and definition of "secure". Indeed, I see this general trend of decreasing user control over increasingly complex and connected hardware as a massive security threat where I am forced to trust multiple 3rd parties who may arbitrarily disrupt my life anytime new "features" or "policies" get pushed out.
It is perfectly possible to securely implement a tamper-evident "I know what I'm doing" switch/fuse that enables advanced control by device owners. However, I'm well aware that I'm in the minority on this topic, so I'm not holding my breath for such features to be implemented.
Now, _will_ I do that? Probably not, but my opinion is that as the owner of the device, I should have the ability to do so if I so choose.