The success of Pixar's 'Soul' shows that Hollywood still struggles with diverse animated films, without adding element of a transformation. But why?

The success of Pixar's 'Soul' shows that Hollywood still struggles with diverse animated films, without adding element of a transformation. But why?
Let's look at The Princess & the Frog and it's origin story; as well as the impact the Disney animated film has. The conversation about Princess Tiana is more timely than ever.
Let take a look at these Disney movies that are based on books. How many did you know?