The difference is between "I can tell this story better/more engaging/more entertaining/more realistic" vs "let's cash in on the success this movie had five years ago"

The Wizard of Oz was a new interpretation of Baum's original story. They put enormous effort into making the new film better than other interpretations, of which there were several. Which is why it's a successful, beloved classic!

The same really can't be said of this week's Marvel/DC remake of whatever they made a few years ago. It's just about being a cash grab and nothing else.

P.S. If you've never heard of the sequel 'Return to Oz', do yourself a favor and watch it without doing any research. Just go in straight blind, it really enhances the experience. If you drink, keep a bottle nearby, you'll need it.