Jez Harris actually spoke a little bit about the difficulties of working with a license in his talk at the Game Career Fair in London in October.
He worked on many of the Harry Potter games released by EA. I think during the talk, he suggested that there are multiple parties who have to sign off on the content, and it was his job as a "designer" to try and ensure that all the parties would indeed give the go-ahead.
Harris also talked about working on Catwoman the game and how it was bascially depressing because he knew going in there was no way to make a good game out of what he was being given.
As much as time and corporate sign-off are factors, you also have to consider that there are developers being asked to work on these licenses and titles, and maybe not all of the developers on the team believe in the project.
Question for you future game designers:
if your first job was to work on a licensed title that you thought poorly of, would you do it just to get into the industry? How would you feel if your first game credit was for something that you _knew_ was going to be crappy? What would you do about that?