AI is a challenge. You can code in to build them a mixed army, but even just figuring out which unit should shoot first, or which ones to target, is always a very tough problem. Never mind mixing in strategies of "What do you build in a city" as well as "should I even go to war" make it so incredibly complex. As well, when you have the carpet of doom, even as a human I have trouble maneuvering my units to get them lined up how I like. Which is a flaw, because I much prefer the 1upt than the stack of doom. Maybe the "correct" strategy is a mixed strategy: you build units, and add them to an "army" unit. That unit moves as a single unit through the map, and has a large and extended zone of control. Then you no longer have unit vs unit battles, it turns into army vs army battles. When they fight, the map zooms into a little mini-game (kind of like Castles II, if anyone played that), where you can then line your units up. Inside the mini-map, the armies could battle it up for positioning inside the hex, and eventually either side would retreat/be destroyed. That would be a huge change to the game and series, but it would certainly be a way to balance the map scale, and would likely let the AI have less to worry about.