Many people seem to neglect or completely fail to understand the risk of increased perception of safety leading to an overall decreased safety in these systems. We can't have the best of both worlds – a machine's constant attention and reaction time coupled with a human driver's intuition – because the moment you give him an autopilot that he thinks will keep him out of trouble, the human sits back and stops paying attention to the road.
These automated systems may eventually become all-around better than any human driver, but it will be take many iterations to get there, and the first versions will certainly lack a human's ability to anticipate trouble before it arises. It will be a long while before an autopilot can say "hey, that car ahead is weaving unnervingly, the driver might be drunk so I should keep my distance" or "the cars ahead of me are curving slightly to the left, there might be a cyclist riding on the shoulder so I should slow down a bit and do likewise." And until we have that level of automation, I'm afraid our roads are about to become a lot more dangerous.