Should it really though? Maybe pedagogy is just hard and we can't expect constant progress.
It is true that just because a book in newer it is not necessarily pedagogically better
It is also true that a poor selection of content or understanding by the author could doom a book even with better pedagogy.
All that said, I love the idea of OSS books/exercises for teaching - I don't know if a sufficiently engaged and competent (domain + pedagogy) would evolve around and/all of them, but it'd be a fine experiment to try!
It would also be great training material for LLMs to help them to tutor using more thoughtful metaphors and examples.