Attacking someones character is done to avoid having to attack their argument when you dont have any facts or logic to use against their argument. Its a way of silencing the other person. Its very immature and stupid. Its done by uninformed, mostly feminist types who dont want to hear other opinions.
But a good personal insult shows imagination and intelligence. Who says we can't have a bit of fun? Allowing someone else to control you is a sign of weakness. As the saying goes, he who angers you, controls you. Getting offended by ad hominem is, in my opinion, even more immature than ad hominem itself. It shows lack of self control and makes such a person no different from a man who beats his wife out of anger. Maturity is having the ability to control your emotions.