Our approach to parenting is teaching them a lesson on what they did wrong. Like mom21 said it was a lesson in respect, which they did not have the first time we went. We weren't punishing them by torturing them to sit through another service, we were teaching them. My kids most definitely learned their lesson more by doing it like this then just letting them sit in their room for 15 minutes to think about it. They go to a parochial school and are taught about all of this daily. They are taught to respect us, God, and their peers. What they did Sunday was not that.
I have tried many ways of punishing my children, trust me I have a very strong willed 5 yr old who laughs at me when I yell. In our case the most effective form that gets their attention is to teach them a lesson about what they did wrong instead of sitting there yelling at them and then sending them to their room. I'm sorry if you think what we did was cruel and unusual, but I can guarantee that we got our point across.