This is an interesting topic.
I am "born-in" and was spanked growing up, frequently. I was a pretty mischevious kid though (very smart/curious/busybody). Looking back, I don't remember ever feeling abused, and I certainly didn't go to the Kindgom Hall with welts, or bruises. However, my parents were not afraid to spank me in front of everyone in that building. The humiliation was more of a deterrant than the actual pain. That type of discipline worked FOR ME.
Yet, I can name a few kids who were beaten to excess. For some children, spanking isn't the best method of discipline. It's up to a parent to determine what works best, and do that, I think.
I will say that this has become almost non-existent in my area. The only child in my Kindgom Hall that is well-behaved gets spanked (not to excess). The rest of them are total maniacs because their parents are too worn out ot put the effort into disciplining them properly. I don't believe in yelling at your kids. That does no good, and that's what most of them do instead of spanking them.
All of the children that I grew up with that were not spanked, became pretty disfunctional as adults (drugs, multiple sexual partners, etc.). They were self-serving, to a fault. I'm not judging those people, as they were raised in a pretty screwed up religion. But I would blame their current lifestyle more on their lack of discipline as a child than I would on their being raised as a Jehovah's Witness. They are impulsive because lack of discipline caused them to shoot first and ask questions later. Had they been properly disciplined they would have learned to think twice before making some of the choices they made in life. These are still good people @ heart, but just not "centered".
I really think that people shouldn't be too hard on their children at the Kingdom Hall, though. It's tough for a toddler to sit through a meeting without being noisy/fidgity. It's tough for a toddler to sit through a Disney movie without being noisy/fidgity. So how could we expect our kids to be quiet little angels during the meetings?