As the old story says a man in a merc trying to reverse ino a bay is beaten by a chap in a mini. "You have got to have a small car to be able to do that" man gets in his merc and rams the mini " you have got to be rich to be able do that".
Havent you answered your own question. They aid safety and would be very easy to fit to all cars even old ones I would think. Anything that aids safety for the driver or pedestrian etc must be a good thing.