We don't have absolute freedom in many areas because the law recognizes that the general public either is not capable of making informed decisions when that requires high-levels of skill or when there is a high likelihood of bad outcomes due to malicious actors.

For example, if you buy a car there are safety features you cannot turn off without major modifications. Dangerous tools often have safety guards built-in to the design — for example, my blender doesn't say it's my choice whether to keep the spinning blade covered. My bank doesn't say it's my choice whether or not to identify myself when making a withdrawal.

For most people, iOS limiting the damage when they get compromised is a huge plus. Removing that entirely in the absolute position is bringing people back a couple of decades ago only now the malware will have access to their most private moments and data 24x7 rather than just their Geocities browsing history.

Now, consider what that means for something like unlocking the bootloader. Allowing that means undetectable malware, potentially irrecoverable. There's not really a good way around that and even if you try to inform people at the time they enable it that doesn't help if it's done when the device is out of their control (abusive partner, boss, police, etc.), and every on-screen indicator can be faked by the malware vendor. That leaves options like a physical switch in a prominent location which most people aren't going to want to pay for or see, and are more likely to be used by accident than intentionally.