One of the first things you learn as a new driver is not to watch the car immediately in front of you, but rather to watch several cars ahead (and behind). This gives you more time to react to traffic changes, and you still see the actions of the nearest vehicle anyway.
Sure, Tesla's Autopilot will have a much faster reaction time. That will help, but it's not good enough - it only allows Autopilot to react to conditions that the nearest vehicle also reacts to. A deer running toward the road, looking to jump in front of you? A kid chasing a ball toward the street? The vehicle in front of you swerving out of the way of an object in the road? Autopilot doesn't handle any of them, and can't as long as it lacks the ability to see more of the environment around it.
Autopilot is dangerous to Tesla drivers and others because it removes the attention of the driver from the road. It's basically like asking a nearly blind friend with fast reflexes to take the wheel while you read a book or play games on your phone. If it's not legal for a nearly blind driver to take the wheel, Autopilot shouldn't be legal either.