I take no issue in the AI targeting the weakest character if they are intelligent beings. Indeed i always felt its stupid, that archers shoot the guy with that fancy sick full plate, instead of the guy in a robe.
yeah but aggro is a thing even on tabletop. If your fancy knight is just dueling with one single opponent enemy archers are morally compelled to shoot glass cannons, but if you have a raging barbarian in your ranks it should be the immediate threath to be dealth with asap before your own front line collpase and that threath comes to you.
I have seen gnoll hunters taking AoO from my ranger just to keep shooting Gale to death even if i was murdering them