Monsters really should behave differently against strafing and present different stages how easy it is to manually dodge them. Such as...
Rotting Zombie - (new monster!

) Easy to strafe as they are slow moving, slow to react. You can 2x2 them all day long as they are only dangerous in numbers when they can surround you.
Undead Legionnaire - as fast as they were in life, they can time their attacks like the player. If they are not on cooldown they can instantly attack you when you strafe in range or after they turn to face you. (note: Spears and other long reach weapons could also have faster initiative in this regard.)
Ogre - large monsters can sweep attack to their weapon side flank as they turn or hit all 3 squares in front of them. Slow so strafing is still possible but much harder as you have to reach their backside/flank to be safe and be careful not to strafe to the weapon side.
Giant wasps - if you try to strafe them, they just get more free attacks at you. Strafing them is always a bad idea unless there is a better position to fight from or you are trying not to get surrounded.