I simply don't want all euro civs, because I like a bit of diversity and "What If?" Civilization is marketed as changing the course of history, yet if I am forced to play as only Euro or historically dominating nations, what is the point?
Certainly, a majority of the player options should be nations known for historical influence. Yet I feel that there should also be some cultural groups to play. Me? I would find it great to have a seafaring Polynesian group end up dominating the world. I enjoy playing my modded Zawditsu of Ethiopia, and the thought of a black female's empire dominating the planet.
Those kinds of crazy "what if?" scenarios are lost when I'm re-enacting the Dutch and British fighting for naval superiority. It's boring to throw in all of the Euro seafaring colonial powers. To me, it's dull to sit in the rigid confines of history, where I now have 2 new Middle Eastern civs, when I could do with possibly one: Israel. I like regional diversity. I like the Khmer and Polynesia, Ethiopia and Mali, Australia and Canada. They add dynamic -- differentiaton. Play the World greatly enhanced this by adding two Asia Minor/Arabic civs, two Asian civs, and two generally distinct Euro civs. The only ones I didn't particularly feel "fit" the game were the Celts and Carthage, yet they still add that distinct flavor.
Yet out of Conquests, the only Civs I feel that have some true distinction are the Inca and the Dutch. Sumer and the Hittites, while historically important, lack that distinct characteristic that identifies it from Babylon. Portugal -- another seafaring power -- is eclipsed by the more identifiable Spain. The only one that toes the line -- the Maya -- I feel is seen as too akin to the Aztecs, even though I am familiar with their differences.
The point is this: historical merit, or distinct gameplay?
Players understand what makes England, Russia, Germany, France, Spain, and the Vikings very distinct entities. They understand Classical civilizations such as Rome, Greece, and the Ancient Egypt. They familiarize with groups such as Aztecs, Native Americans, and Black Africans. China, Korea, and Japan are distinct and approachable Asian powers, Monoglia is a category all its own, and surely we know of the unqiue Ottoman Turks and the tribes of Arabia.
Civ3 Conquests blurs those lines. Aside from minutiae (of which I could provide for almost any civilization), what is so distinctive about the Hittites or Sumer? What makes Portugal so different from Spain? In a toss-up between the Khmer or the Maya, which is ultimately more distinct and under-represented?
You have the option of "equalizing" all of the Civs by disregarding the unique features -- so what is left? Name recognition, plain and simple. And with name recognition should come the wild-card of playing from as many distinct regions as possible. This isn't a recreation of history, it is fiction -- and I think that Firaxis lost that with their latest selection of playable civilizations.