It shouldn't be "I'd never hit a girl." It should be "I'd never hit anyone". No violence against women is a good thing, really it is. But why are we focusing on one part of the population? Why not no violence against ANYONE?
It'd probably be more effective. If someone's in the habit of solving problems with their fists- then when the logic center of their brain takes a vacation and anger takes over, they're more likely to punch a girl (or anyone, for that matter) than someone that's never hit a person in their life. Not that this is foolproof logic or anything.