In cases where you can genuinely just flip a switch and get back proper access to the machine I don't mind it that much, but these "we must restrict the user for 'security' reasons" things usually don't stay like that forever.
Yeah, that's one of the ways these "optional" "security measures" often become non-optional. Android is a prime example of a system where this has already happened: sure, you can root your device (if your manufacturer allows you to), but none of the software you need.
Another way is simply for the manufacturer to lock down the bootloader/BIOS and not let you disable "secure" boot, as is also common in the Android world.
Or do you mean that certain programs (like one mentioned by sibling) require the switch to be on?