The Question and Answer section for The Wonderful Wizard of Oz is a great resource to ask questions, find answers, and discuss the novel.
I've never thought about it but found an interesting article for you to look at. Scroll down to the seventh paragraph. Note, the article deals with the novel..... not the film. I hope you find it useful.
This is a personal opinion question. I personally would not change anything but your answer should be your opinion rather than mine.
This question calls for your opinion. I love fantasy novels of all kinds, thus, I would recommend reading this novel purely based upon its creative style. Anytime you need to use your imangination...... it's a good thing.