Indeed. The AI needs some concept of dodging arrows as a whole. I wonder whether it is possible to add a concept of "enemy's arrow range" and try to stay out of it unless totally necessary.

For example, when defending a siege, AI just runs around on the street to become mobile targets of enemy archers outside. One time I had 6 regular archers in the army, and they shot down everything, including generals, that joined the parade behind the gate.

If AI knows to hide behind a tall building and wait till enemy rush in the gate, that will be more interesting. :)