I thought the same myself. What use for Party-Formation, if your Main-Character isn't an Meele fighter on the Front. Than again i thought, however, if they would implement it that way, that your Party takes Formation ones the fight beginns, it wouldn't be that dynamic anymore and would forgive to much, like if you mindlessly run into enemys/fight/ambush with your Mage or such.... I don't know an proper solution, maybe for Explorer-Mode?
