Whatever is said to children, about Jesus, is what I need to be an example of; so hearing their sermons can alert me and correct me to how I need to be with children. Things for Christian children can apply to me, including how I need correction. I mean, how in my church, we have ladies who preach the word to our children, and I can feed on what they say, plus I can later repeat things they say, to the children at different times I am with any of them.
Of course, I do not know what your pastor preaches to the children. If a message has, "be nice", and nothing else, yeah I'd have a problem with that.
Also, do you have adult groups and midweek prayer and bible?
And possibly you could speak with your pastor and see what your pastor has to say about this.
The pastor needs to lead us, not the kids.
I think we should share our most real and mature people with our children, in ministering to them; they need to see how our most important ones are interested in them, that we give them the best we have.
Also, it may be, how the pastor is finding out what is going on in the homes. And possibly certain information means a number of adults are coming to church, but not living it at home; and so the pastor could be trying to reach those slack parents, by saying what the children can understand and bring up with their parents at home.
And possibly the pastor is backing up the parents, by saying in sermons what parents have been telling them, at home.