Originally Posted by
Alhanelem
The whole reason these spells do less damage to multiple targets is so that they aren't unequivocally the best spells in all situations. Even FFXIV and other MMOs also do this with most AoEs doing less damage to additional targets- such that you need a certain number of targets before the AoE is worth using. If they made the damage flat against all targets, they'd have to lower the base damage to compensate, such that you would need more targets for the spell to be worth. But I don't think anyone wants that since people often take the tradeoff of paying more MP to get a bigger spell on a single target.