Back to the original point of the article it is important that international standards limiting such devastating weapons be enacted and enforced. Even Assad after being caught using chemical weapons was forced to step back and many robotic weapons, especially autonomous ones, should probably be in the same category for the same reason. These things are going to be developed so we need to act now to limit their use not wait until a calamity has struck.
One of the reasons I'm skeptical about the importance of this is, I guess I still don't understand what the nightmare scenario is. You call these weapons "devastating" and say that they will lead to even more death and suffering than currently existing weapons. How? An autonomous robot with a gun can't kill you any more dead than a human with a gun, and as Assad and Putin have demonstrated the lack of robots didn't keep them from just sending humans instead.