While I sort of intuitively agree with you, I think there's a certain amount of circularity in the argument - any problem will seem to have well defined metrics once you've built and studied a machine which can solve it.

In the sixties, chess was thought to be a problem that required intelligence since it couldn't be brute-forced. We now have machines which can play it well, without brute-forcing, and yet it's seen as entirely procedural.