Prepared lines come in handy in many of life's situations. They are useful for getting points across in a memorable way and they make for effective on-the-spot rebuttals.
A mind well-stocked with prepared lines is a mind less likely to suffer l'esprit d'escalier.
Suppose a feminist argues that men have no right to an opinion about the morality of abortion. Without a moment's hesitation, retort: Arguments don't have testicles!