the Pitties I've met have all been really sweet. I personally love GSDs and Rotties. You are right, the issue is not the dog, and with the wrong owner, even a small terrier can be a terror. Some breeds do require more time spent training them. So there is that. But I take issue with breed-specific discrimination.
However, unfortunately, if I was renting out a place, I might not have a choice because of insurance rates... so having someone being willing to get their own insurance would be a big plus in that situation.