It would be just great if only the AI was good enough to inflict substantial losses on your forces, even when it got beaten.

I consistently inflict 6 to 10 times the losses on the AI that my own side suffers, in battle after battle, almost regardless of the odds. Some battles now I'm only getting 5 or 10 dead guys, sometimes none! And the mainstay of my armed forces is nothing more than the humble Greek levite, one step up from peasants.

If the AI could at least maul your own armies, it would stop you from expanding so fast and deplete your coffers - which would in turn give the AI more chance to recover its own losses. So apart from the extra fun a good AI would provide, it would also restore a lot of the currently missing game balance.