Having worked for a company producing software like this, the EHR and Practice Management/Billing components were essentially separate products. Analytics was separate as well. Those were the three big tentpoles, and they would all talk to or depend on each other, but shared very little code and were of course doing completely different things.

You're kind of right though in that it never felt like we did anything because it's what patients or providers wanted. We didn't do things if we were afraid providers wouldn't like it, but a lot of work seemed to be mostly driven by regulatory requirements (meaningful use, icd10, etc.).