Movies expanding universes?

This is about something that has been on my mind for a while. I've been thinking with book to film adaptations that maybe it would be better if they took a different approach. They just adapt the same story of the books and only give audiences what has already been done. I've been thinking maybe rather than adapt the same story it would probably be better to use films to create new stories for the worlds established in books. These last few months I have seen some movies that did just that. Here are a few examples.

These books give the back stories of some of the legends we've grown up with from our childhood, like the Tooth Fairy and Santa Claus. However the time came when a movie was adapted from these books. This was the result:

It is definitely something to sit down and watch. This film didn't try to adapt the stories of all the books into one. Instead the film's plot takes place after the books have occurred, in the present day. I will spare you the details of what happens in the movie so if you still haven't seen it nothing gets ruined. I did some research and found out the author was involved in the making of this movie, and he was trying to make it a new story. I say he did a good job.

This book, also by the author of The Guardians of Childhood, is one I haven't been able to look into yet. However this book was also adapted into a great movie. In case you're wondering which one, here it is:

I would definitely recommend seeing this movie if you haven't already. From what I was able to find out online the book had a different story from the film, yet from what I found out it almost seems like the Leaf Men were still living out their lives when the events of the film unfold. Both Epic and Rise of the Guardians were well received, financially and critically. There's just one more movie I'd like to mention:

This movie is supposed to be the backstory of the all famous Wizard of Oz. From what I've heard it uses several elements mentioned in the books yet it still seems to be an original story expanding a well-established universe. I plan to see this film this weekend so I'll let you go now so you can work on whatever it is you plan to do. Thank you for your time.