I tend to think in more holistic terms and not focus so much on the individuals. I think society might improve for everyone in it if the practice is eliminated because - and now I'm only scratching the surface - those who would otherwise be beaten might be happier if only for the amount of time they'd otherwise spend getting beaten, they might be less aggressive / less criminal on average and in turn cause less problems for other people in society.
Violence leads to many things. It may cause conformity in difficult children, but is that all? The studies I posted a couple of posts back indicate that there are negative effects on society from corporal punishment.
I was a good boy, but I was a rather difficult teenager, believe it or not.
If my parents wanted to prohibit me from doing something, I'd ignore them or do it without them knowing about it. Then and now, if anyone tries to force me into anything, I get fiercely defensive and I've been like that since I was a toddler. Had I get smacked around more, I think maybe it would just add fuel to the fire that was my frustrations and anger directed at my parents when I was a young teenager. It's hard for me to say, though.
However, I still think I've turned out well without smacking and I think my upbringing is an example that corporal punishment is not needed. Not where I come from anyways. I consider myself a productive and functionally sound member of society.
edit :
About the "me, me, me" mentality, I think I see it here too and I'm not sure what it comes from. I guess maybe the increase in freedom and material goods. Remember however that raising someone without corporal punishment doesn't mean there are not other ways of punishing children. Indeed, I believe you do need negative consequences for negative actions, but I believe you can use stuff like "timeouts" instead of slaps.