"Baum screwed around with Baum" from one book to the next.
He had a right
to do so: it was his own
stuff. Not so with moviemakers screwing around with his stuff for no valid reason, in ways that were either utterly pointless, or detrimental to the story.
Just as Alan Dean Foster has been known to screw around with his
own stuff (if I remember right, some of his Humanx Commonwealth books say that, at least until the Ulru-Ujurrians built the Teacher,
and figured out a way, no KK-drive starship could even closely approach a planet, much less land on one, and yet other books say that certain small KK-drive vessels could indeed shut down their Caplis generators to make planetfall; likewise, there's at least one Commonwealth book that talks about the Thranx taking up body surfing, and even teaming up with a Human partner and acting as a living surfboard, while others characterize the Thranx as being deathly afraid of immersion in water, because their breathing spicules are along the sides of their bodies). For that matter, Tolkien screwed around with his
own stuff, as well, but that doesn't mean I particularly cared for what Bakshi did with it (personally, I'm much happier with what Rankin and Bass did with Tolkien, and haven't yet gotten around to seeing more recent big screen treatments of Tolkien.)
Now, I will
admit that the last time I saw the 1939 MGM Oz, Judy Garland was still living. But the heavily abridged Little Golden Book of Road,
and the even more heavily abridged pop-up book of Wizard
were far more faithful to both the letter and the spirit
of the original material than any
Oz movie I've seen.