From my experience with a couple health related start-ups, I would suggest that the lack of good health apps has much more to do with the current state of the health care system, and less with entrepreneurs familiarity with healthcare. The main problems that make innovation difficult are:
1) Government regulations - healthcare is and has been an important political issue, and because of this there is a mountain of legislation that must be accounted for when operating in the field.
2) Healthcare bureaucracy - The interlocking relationships and ecosystem of healthcare from Patients to Doctors to Hospitals to Insurance Companies to Government is even difficult for insiders to navigate.
3) Fear of liability/litigation - Healthcare is a scary place for "bleeding" edge technology, and few institutions are willing to be operating there.