We can edit, directly observe, and record/playback simulated brains. We can test ten million different models on top of a recorded simulation and see which one fits best. Eero doesn't think we could learn about how the brain works by simulating a trillion slightly different permutations on a brain, or (maybe more ethically) small subsystems of a brain, and observing how each behaves?
Sweet god, the economic implications! http://mason.gmu.edu/~rhanson/uploads.html
Horrifying, maybe, but I don't see how people can get away with suggesting this will never be valuable to anyone.