Only a galah, a totally irrational person would argue that a person's harmless pet should be banned because it looks like something that some people refer to as a "pitbull". However, a rational person would argue that a person who treats a dog badly and turns it into something anti-social should be banned from owning dogs. They would also argue that a person who happens to own any dog, whatever the breed, that has a propensity to attack should ensure that that dog is properly housed so that it does not get the opportunity to attack. If the owner fails in this duty, they should be banned from owning dogs. People who want to ban a dog for no higher reason than its alleged breed are only hurting many innocent pets and their owners.
Who says the arguments were based solely on the animal's appearance?
There's lots of legal/statistical evidence we didn't hear, maybe some of it is quite damning towards pit bulls - consider the mere fact that the ban wasn't tossed outright.