I've been hearing about people in colleagues and unis build robots, and program them for years, all the while the robots bumping into chairs and the "creator" of them scratching heir heads. Robots are 90% a programming problem, 10% hardware.
A robot needs to adapt to the changes in the environment. You can build an entire robot, put it in the environment, and hope the 100 ton automated tanker does not drive into a house.
But then we got this thing call a computer, and their power got rather high many years ago. If most games cannot get AI right, what hope is there for a robot? Why waste costs into making many many designs, when you can iterate virtually, and make just a few (see SpaceX)?