nothing to do with the breed, its more of the TYPE OF PERSON, that is attracted to these breed of dogs. Ive owned Rottweilers, Boxers, bullmastiffs and Dogue De Bordaux's and none have been a problem. People are bitten by other breeds everyday but due to the size/strength of these dogs it goes unheard off.
Ban the scally's and chavs wanting a tough looking dog these crimes will go down, but problem is backyard breeding look how cheap staffy pups are, bred often with bad temperaments due to that.
I've got a friend who reasons the same thing and he's wonderful with his pets so who am I to argue?