I think they should be charged with criminbal negligence or whatever it's called, at least. It might have been an accident, they might have been responsible owners (but something just went wrong, like a gate broke). That's for the courts to decide.

My aunt used to have a rottweiler that could act really mean and vicious, yet was an absolute sweetheart once you knew him (except to other dogs, they had a few 'lawsuits' because he wouldn't always play nice...). I don't think calling for a ban would do much good, like lemur pointed out, they'll just breed a slightly different dog.

Make no mistake, rottweilers aren't bred to be family dogs and i'd never let one near small children, even if they knew the dog.

I think checking the breeders might also work, a lot of dogs are inbred, which can result in 'abnormal' and aggressive behaviour. Checking a dogs breeding line (and making breeders accountable if they break certain norms) could do wonders.