Just to add to that: I imagine that the makers of the first pacemakers were doctors who were better in tune with the need than the patients. In fact, I'm pretty sure that doctor, not the patient, really counts as the target market. He's the one the diagnoses the problem (and understands the need); he's the one that actually orders the devices; he's the one that actually orders the devices. The patient generally only needs to know that he needs one, and that it's going to be installed.

In the same vein, I'll bet that if actual accountants were to design a piece of accounting software, it would probably rock pretty hard. (Assuming of course, that the accountants in question were also competent designers/developers.)