If you spend a lot of time on your boat, you will do what you do. I don't mean that to sound simplistic, but if you eat lunch out frequently when on land, you will find ways to eat lunch out when on the boat. If you use the microwave frequently at home (and who doesn't?), you will appreciate having it on the boat. We use ours all the time.
The more comfortable (home-like) you make your boat, the easier it is to spend extended time onboard. I have heard folks say they want their boat simple to get away from it all... I don't subscribe to that theory. Decide how you will use your boat - if you are going to spend enough time onboard that you will want to prepare food, a microwave (and a way to power it) will make that more convenient.
Best wishes,
Jim B.