I have some darker interpretations. If you look at pictures on childrens school bags, workbooks etc. the boy version is a spiderman sending the message to hang on net ropes like some idiot tarzan and the girl version is some little magic fairy princess sending the message just be there, be pretty, don't do much. So both are very, very detached from what they are supposed to do at school or in adult life. It is a "be useless!" kind of message. Is it perhaps an anticipation of a world where 80% will be unemployed?
Without this hypothetical anticipation of a world of 80% unemployment, would you expect children's bags, books, etc., to be decorated with pictures of people sat at office desks working on spreadsheets, or plumbers fitting pipes together, or something? Were children's bags, books, etc., ever decorated that way before?
I think the explanation is much simpler. Children enjoy imagining themselves as superheroes, princesses, etc.; movies, television shows, books, etc., featuring such characters become popular; children buy (or get their parents to buy) products...
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one. (Immediately before; refresh the list-of-threads page before posting.)
3. Open Threads should be posted in Discussion, and not Main.
4. Open Threads should start on Monday, and end on Sunday.