Some further thoughts....

Maybe they should seed each campaign so one particular AI faction is guaranteed to get big fast and present a real challenge. It could be as simple as giving one AI faction a LOT of starting money. So when the player ran into that faction it would be much stronger and holding a fair piece of the map.

Some basic coding to keep it troops together also seems in order. Rule one minimum garrisons, rule two no second stack until the first one is maxed, rule three keep best general with the best stack, and so on. That way you would at least get one real battle per AI faction.

And yes I know it is easy say and hard to program.

Or they could work on the multiplayer campaign some more...