This was one of my biggest concerns with going post children. The elders told me it was because children should be "trained from infancy". I forget the scripture, but it is one we all have heard. They should not be in the back having fun because it is not a topic of play, but a serious one that means the difference of their life or death. They can't expect to "get through on our baptism" for to long.
We got talked about because we would bring books, magnadoodles, pencils, etc and also play games with her at the expense of our ability to listen. The elders insisted the only reason I questioned their doctrine was that I was looking for an excuse not to have to ask my daughter to sit through the meetings.
Then of course I started realizing that I wanted my girls to have more opportunity and power over their lives than I did... so I guess it was mostly because of them that I came to terms with my suspicions. So I guess in a way they were right.