The only person who needs an expensive camera is the guy who loves expensive cameras, Rob. You're right. It has nothing to do with the quality of the work. What makes that is a visually-oriented head. You can't buy one. I suspect heredity may have something to do with it, just as heredity conveys musical ability or mathematical ability.
And, Grub, I'm not sure "painter before photographer" actually explains it. I'd say instead that exposure to good visual art is what matters. You don't have actually to be a painter for that kind of exposure.