I don't think you should have kids because it's what people do. I don't think you should do anything because it's what people do. It's got to be one of the dumbest, most childish reasons I can think of, a sort of ascribing away your responsibility. Why bother figuring yourself out, and carving out your own path when you could just follow the herd?

You shouldn't have to explain to anyone. No one should. Married or unmarried, with or without kids. As long as you find peace in your choices in life, that should be all that matters (both to you and those around you).