I would imagine that it's one thing to license a character, but quite another to license the likeness of a specific actor who portrayed that character. Superman has been played by enough people, and existed on his own, for them to be able to make a generic character that people will recognise as Superman. Jean Luc Picard has to look like Patrick Stewart, and then you're into a whole other ball game of licenses and fees. It's one of the reasons why you're not allowed to depict characters from the shows and movies in Foundry missions.