> And your second part is exactly why medical devices are not, or at
  > the very least, should not, have changes done to them after-the-fact.

I don't think this is self-evident. There are already a number of devices on the market that basically require physician tuning post-implantation. Deep brain stimulators and cochlear implants spring immediately to mind, and there are likely many other examples. There are many reasons for this: there may be too many parameters for the physician to realistically adjust intraoperatively, assessing efficacy may require activities that are impossible to perform in the OR (ie observing gait), the parameters may be time-varying, it may not be possible to have the patient awake during surgery, the patient may be pre-lingual, etc.

Even worse, both DBS and cochlear implants have relatively short loop-latencies between the physician "turning the knob" and observing the effect (seconds). There are emerging medical implants where the loop-latency may be in the hours-to-weeks range. That's pretty much going to require tuning post-surgery which in turn basically requires a wireless interface of some kind.

Finally, while updating the firmware of a medical device (eg to give new capabilities) should certainly not be done lightly, but it is far and away preferable to going under the knife again to receive a new device.

Bottom line, the right thing to do is get security right, not limit what physicians can do with the devices.