One of the most difficult aspects of writing books for children, in my opinion, is writing books that parents will want to read to them, or want them to read, while pleasing the children and making it fun. You are trying to please two audiences at the same time.
In my Rooter and Snuffle book series I tried to make the stories adventurous and fun for the kids while at the same time helping them to deal with sharing, caring about others, dealing with bullies, listening to their parents, not taking what isn't theirs, and other issues children face. My picture book "Nothing Stops Noah" is about perserverance, and problem solving.
You have to balance what children want with what parents want and do it without preaching to the kids. Still, I think it is important that children's books teach them something while entertaining them. Character building is important. Reading is about communication, passing on information, learning.
I would love to know what issues parents and teachers would like to see dealt with in children's books? Are parents and teachers looking for the same thing?