What I find tiresome is how some people dismiss gameplay comparisons between Civ and EU on the grounds that "they're completely different games". In fact, there are probably more similarities between Civ and EU than there are between Civ and Panzer General. Despite the obvious differences, there are lot of good and interesting ideas that Civ could take from EU, so I think it's best to keep an open mind when comparing the two games.
As to increasing the number of civs: I vote yes, but it's not just a matter of quantity. It would be great to play huge worlds with hundreds of nations, but that increase in number of playable civs should come with new gameplay concepts that allow for a more complex and dynamic EU-style system: nations that rise and fall as a consequence of rebellions, barbarian invasions (like in EU:Rome), dynastic wars, civil wars, breakaway colonies, etc.
Civ's strategy depth + EU's simulation complexity = the best of both worlds.