It's true that software differs from many Physical Engineering practices too, but why does this automatically make "craft" appropriate? Are Mathematicians called craftsmen because there is no physical output to their efforts?

> We create programs custom built for a purpose, using rules of thumb and our own aesthetic instincts

Software can be general too, it's not the same as, say, making a small stool or chair. Plus, craftsmen are tied to physical constraints too, much like engineers. I'm not sure I agree with how much s/w depends on "rules of thumb and our own aesthetic instincts" though.