Lot's of rear end crashes, you say? How about people get nailed for tailgating more often?
Where I live in the north east, people routinely travel 70+ mph with as little as 4-5 feet between them. It's like the automatic driving car caravans of the future minus the automatic and future part. NO WONDER there are so many huge pileups month after month when most people do not see to even attempt to maintain a reasonable minimum distance between themselves are other cars at speed.
We really don't *need* more automatic features. I predict the majority of people buying braking assist now assume they don't have to worry about distance because "the computer" will "hit the brakes for them". It's like how people with 4WD or AWD assume they can drive full speed on ice.