I've never really liked how much focus the leaders get especially in later games but they're a staple of the franchise at this point, as well as the comical attempts at giving them more personality. I guess you could call them "charismatic" history along with wonders, like there is charismatic megafauna.
I think that's a very good way of putting it. Perhaps unsurprisingly I am following a lot of discussions about the nature and appeal of historical 4X games on places like Three Moves Ahead and Soren Johnson's podcast and one thing that keeps coming up on why historical 4X games are so popular compared to scifi or fantasy settings is that everyone knows what The Wheel is and what the Pyramids are and who George Washington is. I don't even want to say emotional connection but it gives a point of grounding that helps contextualise what happens in the game. People think about their games as "oh this time the Chinese built the Pyramids but the Egyptians founded an island trade empire" and our pre-existing knowledge about the Chinese and Egyptians fills in the gaps or contrasts with game events, so that the game itself does not need to do much to explain what the Egyptians and Chinese are for the player to engage in that way.
If your science fiction game has the Protaxians invent the hyperphase drive but the Sorgoids build a spaceship with tachyon cannons that can mean everything and nothing. Such a game would need to do a lot of work to make you get an understanding of who those people and what those technologies are. Most confusingly don't even bother and that's why these games fall flat.
It's also what makes Alpha Centauri so remarkable as a game because it does invent a weird future setting but uses the tools of the genre extremely well to establish an emotional connection with the weird things in it (just think of the Recycling Tanks quote and stuff like that). And nevertheless it is still a niche game.
Three questions:
1) Are your issues with Civ IV mostly to do with the leaderheads or do they extend to the rest of the game's aesthetics as well?
I think the way units and terrain elements and buildings are proportioned is all a bit too cartoony for my taste, but it was probably a good move at the time to include strategy players with bad hardware and turn the flaw of the limited graphics into a virtue. Like I said above, Civ5 does a turn for realism and drabness and that works even less for me.
2) Do you think some mods significantly improve the game on the aesthetic front (besides Blue Marble)?
Oh definitely. I think the game in its DoC state (i.e. mostly Blue Marble added) actually looks really good. I don't mind the cartoony proportions that much, once you are used to it as what the game looks like it's fine. I don't know if there are major improvements on top of that. I think graphical improvements go more in the direction of variety rather than quality for most mods.
3) Did you ever consider changing the leaderheads to static art (paintings, etc) like some mods do? I assume you might have and there's a good reason why you've kept animated leaderheads as the lesser evil.
With all I said about some of the animations, I think you lose a lot if leaderheads do not respond at all. The diplomacy screen is all you have in terms of interaction with AI "players". If you play the game a lot there is little illusion left with respect to the "realness" of your opponent but it's still better if you have something to cling on to to sustain that idea.
And like Logoncal mentions, it would be difficult to impossible to find consistent artwork for all leaders in the game. I'd rather have everyone equally cartoony looking than juxtapose Baroque paintings with medieval illustrations with Babylonian relief works. Or worse, mix actual historical depictions with artist's imaginations. At least the animated leaderheads are honest about capturing the idea of a historical character more than being a factual depiction of them.
