There are plenty of benefits, but you can also ask the dead person in AZ about the downside of defending a product that isn't ready. A self-driving car that drives itself without the most basic of defensive driving habits simply isn't ready. Ask yourself, why do the reports show that brakes weren't applied?
And here I was, stupidly thinking that was the whole point of a self-driving car...
What's the benefit of a self-driving car that can't be trusted to drive itself again?