So why is Temper, with its undefined potency and duration, a self-target only spell, while Corsair has access to a 25% Double Attack enhancement that affects the entire party?

I'm not exactly keen on yet another buff I need to cycle cast (RDM has the highest enhancing skill in the game; why are all our buffs self-target or single-target only?), but the claim that this would allow RDM to make players into demigods seems somewhat nonsensical when you compare Temper to Fighter's Roll and Ifrit's favor.