... low-level sensorimotor skills require enormous computational resources.

I think this fails to make a necessary distinction between tasks that are algorithmically neat (but computation intensive) and tasks that are algorithmically scruffy (but modest in usage of computational resources).

We should expect the difficulty of reverse-engineering any human skill to be roughly proportional to the amount of time that skill has been evolving in animals.

My intutitions are different (or perhaps I am just interpreting differently). The core neural algorithms of vertebrate locomotion are pretty much the same in snakes, lizards, ostriches, eagles, bats, dolphins, elephants, cats, kangaroos, and tri-athletes. The fact that these algorithms and architecture have been so successfully retargeted to such a variety of gaits and grasping appendages suggests to me that there is an elegant core organization. And that once you understand how it works in one of these beasts, it should be pretty easy to figure out how it works in another.