I had seen/heard/read that the thrust asymmetry was a design feature to help with yaw, and that fewer engines would overpower the design limits of other parts of the airplane, to the extent that everything else would need to be redesigned to handle them (mounts, tail, rudder, etc.)
edit: I believe this is the original video where I saw the above https://www.youtube.com/watch?v=02_geGISTLg