I can see both sides of this. We got married at 7:00 in the evening with the express purpose of discouraging children from being there. They weren't formally excluded, but none attended. We both come from small families without a lot of cousins or other extended family, so it wasn't a big hardship on anyone.

I think the root issue is American style parenting. It seems like kids either run wild or are over-managed and controlled by adults (which distracts from the adults getting to enjoy themselves). The Argentinian wedding you described seems like an atmosphere where kids are used to being integrated into activities like that, where they know how to behave reasonably without having to be the focus of the attention. If we had more of that here, I think more people would embrace children at weddings.