They just have to learn how to ignore does type of replies or make use of the ignore button if they noticed same reply from a particular user and they feel offended by those comments. You can't stop people from acting childish, Irrespective of whether you're wearing a signature, not wearing one or wearing the sig banned message, if trolls or whatever they call themselves wants to attack you they'll.

The sig banned message is passing a loud message to who ever sees it (on their profile). You commit plagiarism, you get punished so I don't support the idea of removing it.