I thought I would follow up the previous post with another good reason for babies/toddlers/children. This reason is on the opposite side of God teaching us how "childish" we are sometimes. He also wants us to know sometimes it's better to be like a child.
Take my sweet Reese. (She teaches me lessons on the other side of the fence as well, don't worry that I singled Reia out previously!) While at church one day she was climbing the stairs at the high school where we hold services. I walked up to get her and she stood up. As I reached out my hands she just started walking like she was on flat ground. Of course I caught her before she took what would have been a very painful tumble. A woman standing next to me commented, "Wouldn't it just be lovely if we were always like that with God. She had no doubt that you were going to catch her. She trusted you so much that she didn't even think about what wasn't under her feet."