Yeah. Taking AOO is especially stupid since they can move out with jump and still shoot xD
Tactic wise, its actually 90% of the time the best call to ignore even the "raging barbarian". Spread out, shoot the weak ones. Even if there is an axe swinging barbarian. A fireball throwing mage is just as much of a threat and he is easier to take out. so...
I´m actually happy about the challange that you need to protect your mages heavily. That was one of the weaknesses of kingmaker, that you could just have your AC70 vivi/monk aggro everyone and not be hit at all while your mages rage havok on the enemy are being completely ignored.