Buying the rights to a book (or work of any art) should preclude changing the original.
Tell that to the censors.
ACO was never released in the UK [until Kubrick died] because he controlled the UK rights...and the censors wanted it changed.
Meanwhile it was changed for release in the US.
Oz saw it the way it was supposed to be...
Edit.....also the book was censored in the US....not just the movie.
Brave New World....