...at the risk of bricking devices and legal threats? Sure. Both of which are concerns with some teeth for such mission critical devices as... your xbox.

Jailbroken medical devices sounds like a great way for a doctor to loose their license, a developer to end up with manslaughter charges, and patients being unable to tell their doctors about their full medical situation, lest their doctors run screaming from the impending liability lawsuit.

I think the correct answer to "let people modify their own devices" is "fix the regulations" not "intentionally weaken security in matters of potential life and death."