1. Compared to the average person in the FDA's population of people who are in charge of evaluating the medical devices, the average person in the population of people who would make fixes and helpful modifications might have more expertise in determining the quality of the device's normal software.
2. It's not as if the people who depend on the medical devices have to take the word of the community of people who will mod the devices over the word of the FDA.
And surely they could hire experts to do the job.