I have actually run into mine before, while walking around my truck. It only has happened once, but it didn't feel good. Having said that, it would be legal in many states to have something hanging out of the back of the truck (distance varies by state) much further than a hitch hangs out.
As far as the insurance industry goes, they may save money for the violator who ran into the back of the truck in front of them but the truck that got hit would probably have more damage. So who should pay the bill? The violator or the victim? I think I'll keep my hitch in.
About a year ago I was riding in my FIL's SUV when he was rear ended. He had recently taken his hitch out. Both of us were sore for several days and his SUV (Mercury Mountaineer) suffered a few thousand dollars of damage. If the hitch had been in the receiver there probably would have been no damage to his vehicle and we wouldn't have been as sore. He now drives with the hitch always in.
I suppose that if I was a bad driver who made a habit out of rear ending other vehicles I wouldn't like the idea of a hitch sticking out.
