"Allen came on for Robocop 2 because it was going to be directed by Tim Hunter, who also helmed River's Edge. 'I loved the script,' which was written by Frank Miller (Sin City), and Walon Green (The Wild Bunch). Hunter left the project and was then replaced by The Empire Strikes Back helmer Irvin Kirshner, who Allen called 'the most miserable human being that ever walked planet earth. I found out later that he didn't want me to return for the role. He then ruined the script, taking the heart and soul out of it. Robocop 2 was missing everything that made the first film wonderful.'"

http://www.tgdaily.com/games-and-entertainment-features/61907-robocop-yesterday-and-tomorrow

It's too bad. He seemed so nice. :(