Because it is our future.
Nobody WANTS to smack their children. But being taught to understand and respect "no" has to start at a young age to ensure you can remain in control of your childs behaviour when they are older. Once the lesson is learnt then the threat is often enough to stop bad behaviour before it gets out of hand.
People now fear chastising their children. Who will see? who will hear? who will report?
This is leading to the ever growing population of children that do not repect their elders, their peers, their teachers or the law.
I would like to see positive support from the government for parents and chastisement. It is even frowned upon to shout at your children and show you are annoyed now. Have you ever tried telling off an animal that has fouled your new carpet in quiet subtle tones and a relaxed body language? Yes, it just wags it's tail and and thinks it's a good thing! Daily doses of puppy poo proceed! It's the same with children, your tone and body language need to match the mood, otherwise you just confuse the poor kids!
The same support should also be given to teachers. Then both parents and teachers can work together to teach the right way for our future generation rather than undermining each other.
I know someone may raise the issue of child abuse/cruelty. I will not belittle that subject in any way. There are a minority of people that cannot tell the difference between a smack and a beating BUT they are there whether you are allowed to physically chastise your child or not.