Are there IP ownership complications?
Are the games themselves too derivative of movies (e.g. Monkey Island being inspired by the Pirates of the Caribbean ride, and thus reverse-retrospectively derivative of the Pirates of the Caribbean movies)?
Would it be too hard to adapt them as comedies, or would they be too boring as non-comedies?
Is the built-in audience actually not as large as I imagine it would be?
Are there some gaming-ignorant egos involved? i.e. what lead to the 4th Indiana Jones using the lame Crystal Skull story instead of the great Fate of Atlantis story?
Is the world simply not ready for Day of the Tentacle on Disney+?