Let me guess, you're American. Or at least part of a Western culture. Do I honestly need to run you down all the reasons why you in particular are so dead set on believing in your moral stand point, to the extent where anyone else's is completely and utterly wrong? See, I, as a male, have this little thing called dignity. If you and I are out, having some beers, and two women come up to us, take our beers, pour it over our heads, call us some nasty words, kick us in the nuts, spit on our neck, mock our loved ones and our cultural heritage, we will both react in two different ways - according to what you say.
You will not do a single thing. Maybe you'll yell at your girl, maybe you'll ask "What's wrong with you" a million times, but regardless of what you say or how loud you say it, you won't lay a finger on her. You'll walk away. Correct?
Me? There's no telling what I'd do to my girl. I might slap her, I might push her, either way she's not getting away with just words. Because the fact she has a vagina does not excuse her of being an absolute asshole of a person. Thus, we go back to the dignity thing. Once my dignity is insulted, it's highly likely that someone will go home with a black eye if the occasion calls for it. I don't care what the gender is, you don't step over people's personal boundaries.
Going back to what I started with, this is a difference in morality based on our different cultures. Not many people know this here, but I'm Eastern European. Bulgarian to be exact. I'm pretty sure as soon as some people read this they went "oh, that explains it". Not to make you think it's a custom here to beat women, we just don't care about the gender. If you are an asshole, you get treated like one. Believe me, there are far more assholes in my part of the world than yours. Living in such a culture teaches you a few things. Things you can't comprehend because you haven't been a part of that culture, which is all fine and dandy.
Please refrain from imposing your belief on what is right or wrong, and generalizing it as ULTIMATELY good or evil. According to your belief system, I'm a piece of shit for even putting a finger on a girl. I understand it, I'm quite familiar with Western culture. According to MY culture, you're an absolute pussy with no dignity, no honor, no back bone, and if you can't stand up to a woman you can't stand up to anyone. It doesn't make you a gentleman, it doesn't make you civilized, it makes you a slug.
Like I said, violence on women or men or anyone is allowed as long as it calls for such a reaction. Women are not invulnerable to being idiots. Evil peope get treated in an evil way. Period.