A bigger reason would be because rear end collisions are one of the most common (according to OSHA, the most common) form of incident. You've seen enough driver distraction to believe that, I'm sure.
A friend of mine bought a brand new Chevy S10 pickup, of the cheapest possible configuration. No options, and every delete that was possible. To our surprise, they let him order it without a rear bumper. He laughed all the way to the bank. Then a year later came a very minor traffic bump, wherein he learned that body panels are not designed to resist impact. The other car drove away unscathed. The bodyshop laughed all the way to their bank.
