In CivIV, the addition of new leaders with each expansion has been very important, as it has so far proved impossible for modders to create new leader models and animations that work correctly. Every time a new leader debuts, it opens up a new template (that hopefully works better for some added leader ideas than what was previously available). For instance, I'm thinking that a good Nebuchadnezzar might be a recolored Justinian with Hammurabi's hat. A good Vicinterix of the Celts might be a recolored Justinian with a painted-in beard. Sulieman provides a great hat alternative that can hopefully be applied to multiple leaderheads, and the inclusion of Hammurabi and Gilgamesh may spell the end of every middle-eastern leader looking like Cyrus with a different colored robe. I also have high hopes for Bodicea as Dido of Carthage or Cleopatra, but who knows.