But why do you say they are working in well-defined problem spaces? No more well-defined than most, I would have thought. Certainly Moore was a pioneer of iterative development and evolving a program (and notation) in the direction of the problem. That's why he invented Forth in the first place.
Edit: Oh, having looked up the Medawar reference I realize you probably mean "well-defined problem space" in the way a mathematician would: a problem space narrow enough to be effectively studied but rich enough to produce meaningful results. Certainly most software projects do not start out in such a space. On the other hand, we don't try to learn enough about our problems to find such spaces. We merely add code. One might almost say we excrete it.