Even if you could legislate that, you couldn't fully enforce it. Its not realistic at all. It would be like trying to ban alcohol because every weekend some drunk idiot gets behind a wheel and causes a car crash.
I think its more about creating public awareness. People need to understand these are not killing machines (that's utter rubbish), but at the same time this is not a dog for a novice first time owner. This is not the kind of dog you leave in the backyard, come home to feed it once a day and ignore it the rest of the time. If you want that, get a Golden Lab. They also love everyone unconditionally and will even lick the intruders breaking into your home and play ball with them.
The Pitbull breed needs puppy socializing from a young age. It needs a stern owner who is a 'pack leader' and takes the lead. These dogs will test their boundaries and are very headstrong. They will walk all over you if you let them. Its a dog that requires your involvement, attention and training. And when you get that right, they are a fantastic dog to be around.
I find it quite amusing that those that vilify the breed the most, are usually people who have never owned one, or haven't even really interacted with them at all.