We studied the supposedly didactic nature of

Victorian children's literature when I was doing my teacher training.
"School Librarianship One" effectively disguised that the subject was really about children's literature. Very few people did it. I was the only person in my year who did the subject and I had to attend a different college in order to do it. Even if they had said "Children's Literature" I doubt there would have been many takers. My fellow students showed little, if any, interest in children's books. After all they were going to be teachers of primary school children. Books were something children read for pleasure, in their spare time. It was not something you needed to know about. I often wonder how they managed to teach English.
But School Librarianship One was the subject I enjoyed the most. There was a good deal of reading involved but I was already familiar with most of the books, even the Victorian era books. I knew Stalky & Co, Tom Brown's Schooldays and At the Back of the North Wind. I knew my Carroll, my Sewell and my Twain. My father read Rosetti to me before I went to school and my paternal grandparents gave me Tom and the Water Babies for my fifth birthday.
I was supposed to look at these books in a different way now that I was "studying" them. I was supposed to see many of them as didactic. I was supposed to appreciate their religious, moral and social lessons or commentary. Reading them as a child however I had read them as stories. I know I felt sorry for Tom but it was a story. It was not a social commentary.
I read Eve Garnett's "The family from One End Street" and John Rowe Townsend's "Gumble's Yard" in the same way. They were stories first. I came to the social commentary later.
I have been more conscious of the "social commentary" in some of the more recent children's books I have read. In the 1980's and 1990's there were a rash of books about AIDS and other "social issues". Homosexuality, long a taboo issue even for adults, has been explored. Issues about race, religion and refugees have been explored.
There is nothing wrong with doing this but it seems to have been done very self-consciously. Some writers have sat down to write a book about "death" or "divorce" or "religious intolerance" or the "refugee issue". They have not sat down to write a story.
In School Librarianship One some of the early children's literature we read was criticised for being didactic. It has largely disappeared from the library shelves. "Black Beauty" is still on library shelves. So are some of the other early works I read.
I think it is the story which counts for children, not the social commentary.