You...could be...healthier?
In fact, frozen food, a primary candidate for the microwave, may be just as good as fresh food, sometimes better depending on the process and on how fresh the "fresh" food is. Also microwaving is actually a healthy way of cooking things.
It all depends on what you put inside your microwave. Healthy food is healthy, junk food is junk, but the microwave has nothing to do with it.
As you say healthy food is healthy, but there may not be a lot of it available in your local freezer aisle. Or there may, depends where you live and shop I suspect.