Because kids are physically smaller, there's an assumption by people who haven't read a kids' book for a long time that their ideas and themes and problems and ambitions must be commensurately smaller and less important. I would venture that sometimes the opposite is true.
Kids who are nine, 10 and 11 are pretty sophisticated readers; they know that there isn't always a good outcome every time and that problems don't always have solutions.
Kids aren't political, but around 10 years old, they are beginning to develop the moral grounding that might later, in their teens, develop into their first real political perspectives.
I wrote stories as a kid just for myself. One day, some of the kids in my class found some of my stories in my bag, and I was deeply embarrassed until I realised they enjoyed reading them.
Step-parenting and being a step-sibling presents a lot of exciting opportunities. When families break up and re-form, there may be less order, less certainty, and a bit more trauma involved, but kids can end up having half-a-dozen parent figures.