The AI does not know how manage archers at all due to two reasons:
1- AI puts its archers in front and try to move them as fast as it moves infantry units. It is good that the AI tries to rush the player with its infantry (otherwise the infantry would get wrecked by our archers even easier), but AI archers trying to keep the cohesion with the whole army means that they rarely fire while infantry is moving forward. AI should "release/separate" achers from the army cohesion as long as they are in rage to start firing. There is not really need to keep cohesion between infantry and AI, and they could move at different speed when archers are shooting.
I think TW devs do this in order to avoid archer units being flanked and ganked by player's cavalry, but the result is much worse performance in 100% of the battles.
2- The second issue is also related to archer units trying to avoid being flanked and ganked by cavalry. Archers are in some kind of "skirmish mode" and they try to run away when cavalry is attacking them. This does not make anything good for these archers because they stop firing while keep dying because cavalry is faster and able to catch them. They should just stand and keep fighting and they would perform much better than the do currently.
Then we have the issue with AI infantry which do not block projectiles most of the times. The thing is that watching again some of my videos, it looks like the AI infantry is sometimes able to use shields pretty effectively but this just happens eventually. Check this video at 6:10 and compare with the video in the first post.
If TW would make infantry able to always use shields in this way, plus making a better use of archers, the battles would be much funnier, enjoyable and challenging. Thanks.