Have you ever been in a beastman camp or fireplace and seen two of them talking? Have you ever attacked one of them out of sight of the other and when it comes to attack you the other one just carries on the conversation?
Mob aggro behaviour is just ridiculous at times, I mean when they're just sitting around next to each other I'm willing to accept that maybe they're just so oblivious that they didn't notice their friend get hit in the head by a shield/axe/spear/spell. But when they are in mid conversation and one of them walks off to do battle, I refuse to believe the other wouldn't notice that...
I dunno maybe I'm being stupid but it bugs me. So all I'm suggesting is maybe make beastmen/bandits link with other beastmen/bandits, but only when they are looking at the mob that gets attacked.