We need cheap IP
What developers need is a cheap source of IP that originates from a medium which is consumed by a significant proportion of the target market. Also, the cheap IP should come from a lower cost base than the developed project unless it is an extension to an already successful line of products. George Lucas can license his Star Wars property for toys and games, but a maker of toys or games should license IP from an animated blockbuster movie at their own peril because Disney will extract a significant license fee for the privilege.
UPDATE: Hollywood gets this model right. There is a fierce competition by screenwriters and authors of successful books to get their ideas translated into film. Sometimes studios pay a large amount for a script but it usually represents no more than a small fraction of the overall production budget. However, there is enough cache attached to the project to get big name stars on board who then lure their fan base to see the movie.
Video game production lacks this essential aspect of creativity. Publishers rarely look for lower forms of IP, but instead attach themselves to high-profile licenses which cost them an arm and a leg. If they looked beneath themselves, instead of up, more ideas could be developed and greater profits achieved.