Why do some people have issues with corporal punishment?

A lot of people will say that children who experience corporal punishment at home usually turn out to be more violent when they grow up, and less attentive at school. Well, the definition of discipline in my house when i was younger was "If you don't do what you're suppose to, you're gettin a whoopin". And that seemed to be the most effective. And most of the times i got a butt-whoopin, i knew why i was getting it. Now that i'm older, i get excellent grades in shcool, i have never once gotten into a fight, and above all, i know the difference between what's right and wrong. And now that i'm older, my mom has no more need to whoop me, because she knows that she has "disciplined" me to the right thing, and that is what i try to do (most of the time). Of course the sensation of getting whooped/pinched is not pleasant at all, but it has still trained me to be a better person. So how could society view such a thing as socially incorrect? It worked for me, and it worked for my sister, and not to toot my own horn, but i'd say we've matured into pretty decent people.