I was spanked as a child, and I do consider it a form of abuse. Spanking never did anything for me. My father did it out of anger and even admitted that he would have done it differently back then. He has since apologized for it. His only means of disciplining me and my brothers was to yell and spank us, and that was his way of instilling fear in us. We were never told WHY we shouldn't do the things we did and what the consequences would be later in life if we didn't learn now, just told "NO" and then the belt came out or some other stuff (wooden spoon, hanger, hand).
I don't even think a light swat on the bum is appropriate. I get the explanation behind it as I have read plenty of responses on spanking, but I still don't agree with it. To go so far as to hit your child, soft or hard, 'cause that is technically what you're doing (not trying to put any emotion into it), so that you instill this idea in their head that they are going to be physically hit if they do something bad seems ridiculous to me. I believe starting from the moment they pop out of the womb that parents should: A) teach their children the proper way of behaving, B) model the proper way of behaving, C) correct the behavior with punishment other than hitting.
This is just from my experience, but the people who spanked me and the people I know who have children who immediately resort to spanking have little to no patience. This is something you need to have with a child. You need patience and you need resilience, and you need not to waver in your stance. My own parents folded into their anger at what I did wrong and resorted to spanking first. There was rarely ever a moment, with my dad at least, that he would actually TALK to us about what we did wrong and why we shouldn't do it. He rarely took toys away, stuff we really loved to play with and would be devastated if we couldn't have, never put us in time out, never forced us to do chores as punishment, etc. He just went from zero to ten and BAM!
What I see and have recognized over the years is a lot of inability to stick to other forms of punishment because they don't get immediate results. Sure, a spanking will shock a child into perhaps stopping what they're doing at the moment, but what are the long-term consequences? What is your child really learning from you hitting them? I'd suggest taking a look at some studies on the effects of spanking. They're very interesting and I can say for certain, with my history, that I was negatively affected by being spanked. There was no benefit in it for me or for my parents.
tl;dr i view spanking as a form of child abuse, and that more parents should be proactive from the start using various forms of other non-physical punishment