They only signed Keaton for one movie?
What are they thinking? They obviously kept Vulture alive at the end of the movie, why not sign him for at least a second movie and use him for the Sinister Six.
shareYep. Not unlikely they didn't want his villain, as great as he was, to overstay his welcome, or they pretty much didn't see a legitimate reason to have him return anytime soon. I can still see him be brought back though, especially by popular demand.