>> Picking up and putting down a cube from a known location, and visually analyzing it, are both solved problems. It's a boring and arbitrary restriction.

In that case, solving a Rubik's cube is a solved problem. It's become boring thing to watch machines do it. These machines are somewhat impressive in their own way, but the task they are doing has no point. I'd even say because "solving" is no longer relevant, the machines should be manipulating the cube in known (non random) patterns since we're down to comparing speeds.