It's not as uncommon as you think. I'm both a paramedic and a developer for an EHR, and we have a number of other medical professionals (including a physician) in various product related roles.
I know that EHR companies surely employ both engineers and medical professionals, but are they able to freely innovate and explore, or are they bound to top-down bureaucracy with, as another responder mentioned, misaligned incentives? The kind of thing that I imagine would be a fully open source, open standards implementation that could allow easy portability of records between all providers.