It's tricky. Sometimes changing things truly is a creative act. A big portion of Disney's portfolio is from retelling European fairy tales: Sleeping Beauty, The Little Mermaid, Little Red Riding Hood, Hansel and Gretel, etc. It would be hard to argue that they added nothing of value when they remade those fairy tales. In many cases, people wouldn't recognize the original stories because Disney changed so much.

OTOH, it seems like bullshit when tiny elements are changed. For example, the Conan-Doyle estate has sued because although Sherlock Holmes was in the public domain, they said that was only the stories where he was aloof and analytic. They said that in stories published in the 1920s he was more capable of empathy, so any depiction of Holmes where he was empathetic infringed on their copyright.

If I were on a jury deciding this sort of thing, I'd require that there be something brand new. For example, Beauty and The Beast is public domain, and as long as someone is making an animated movie based on that story the default assumption should be that they're inventing new aspects based on the public domain story, not based on the Disney movie. OTOH if they have an animated candle / candelabra, it's reasonable to assume that infringes on the new character created by Disney.