Time is the enemy
Thanks to the regulatory process, medical devices are typically years behind the state of the art, particularly since the manufacturers have plenty of incentive to wring as much lifetime out of the product as possible. Any change to any part of a device requires regulatory review, so forget about weekly patching. Most manufacturers will focus on a new device rather than upgrade an old one. In 5 to 10 years time we may have sophisticated online threats going against devices that are designed with older, obsolete threats in mind.
In other words, even if the problem isn't real now, it will be very real in a few years.