TW is a niche genre. It's not really RTS, certainly not FPS, nor is it RPG.
Exactly, though this has been/is the case with all TW games, from Samurai through Knights, Legionaries, etc. We could argue the same for R2TW. CA would probably bring back the screeching women, arcani, flaming pigs, chanting druids and super legionaries - only this time around no one would be able to mod it...
You forgot the Spartans with no armour whose shields did almost nothing and who had almost no defensive skill, but had millions of hitpoints. :P
I don't think the games are targeted particularly at "high school students", more so the "casual gamer" (supposedly anyway). A sparta total war would actually be a good idea. A huge map encompassing as many cultures as possible does not necessarily equate to a better game. Sometimes less is more.
I don't think the game(s) is really marketed at history buffs.

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