Is it moral to charge for food? Water? Heat? For tutoring or teaching? If I've learned something in my years and I want to make the world better by passing it on, through software or any other means, I'm morally
obligated to find a way to sustain it. I personally also feel morally obligated to educate my children so that they can do the same.
The best model man has yet developed for allowing people's talents to be used to their fullest is business.
I disagree with your implication that I am somehow immoral for selling software. In fact, I am a little annoyed.
(Edit: but I did upmod because it's an interesting POV that deserves to be heard.)