Angels are the fun, at least the way the culture pictures them. Those chubby little cherubs, who wouldn't hurt a flea. For these things are just as much a matter of childlike trust in God's Word as are the angels. Being childlike when it comes to heavenly things isn't such a bad thing. It is only with the humility and wonder of a child that we can rejoice in the angels.
Children believe what they are told, especially by their parents.
The Lord has dire threats of millstones strung around the necks of those who cause His little ones to fall from faith. If that isn't a good argument for bringing the kids to church, I don't know what is. And He has a word for those who are annoyed at the presence of children in His church. To receive a little one in the name of Jesus is to receive Jesus Himself. Besides, their angels are keeping a special eye on them, and you wouldn't want to get on their bad side.