I guess they only have programmed one way of AI acting. With higher difficulty level the AI gets additional bonuses but not other acting rules. And the two rules I find out are: 1. don´t hunt and kill the only general of the human player that´s let him quit playing for at least one day or longer, that is not good. 2. don´t bring the gamer to cry in his first couple games by starting a two fronts war and smashing him. That would make human consumer angry. Maybe they switch this two rules easily off with the next patch when the gamers have more frustration limit.