Their audience is basically desperate for a better AI that does better strategic and tactical thinking rather than pathfinding, weighted decision trees, and a couple of high level heuristics.
Here's what I and I'd gather many others would want instead: for the AI to go through the dev game logs, and perhaps even end user game logs, and then learn from what humans are doing, so they behave more like them. And then re-inject that into the game so it's something of a challenge to play without needing to give the AI some serious bonuses while playing.
As things stand the AI is so bad you can start as a purposely broken one province nation and still turn into a major power. [0]
And if you're thinking "no, the AI will trash them and they won't find it fun," here's a thought: right now, the AI is so bad that the only way to have some fun is to give it insanely large bonuses. But much like in a game of Go, as a player I'd much rather get those boosts myself to overcome a much stronger AI opponent.
The same holds for other 4X games, like Civ.
Playing Chess or Go against a computer used to suck. It no longer does thanks to how much better AI got.