It's funny, I liked SMAC exactly because it did not have any historical baggage. This allowed it to have more "pure" leaders and historical projects (I can still quote Prokhor Zakharov and Chairman Yang by heart) in a way that regular Civ never could, because historical leaders just can't embody an ideal quite as purely as a fictional character. It also allowed for a "story", even though in hindsight it was pretty thin, which is not really possible in regular civ because we pretty much know how it ends...