They see this character as somebody who can be successful, and so making a movie about her, which will help promote the theme park, which can, in turn, promote the movie, is just about the most Disney move that there is.
Disney is also all about the corporate synergy and the company’s ability to tie its movie and theme park businesses together is unparalleled.
The fact that Disney made Redd a walk around character at Disneyland at the same time that the new part of the ride opened shows that Disney wants to make Redd a popular character.