Although this may present with an ongoing dialectic, the tension may exist in the reality of institutional arrangements rather than the theory that tries to explain them. Theories do not always relate to situations of harmony, but you are right that usually when we think of functionalist theories, we equate equilibrium with harmony. Also interesting is this trend of market-driven health care to transform people into cases. They have little loyalty to theories nor are they as entrenched in the sociological perspective and bring a lot of insight to bear in such discussions. Also it gives the teacher the chance to be the sociological voice to hopefully add to the student's understanding as well.
Sociology changes the world.