Deckard bloody Cain

Why does it cost mana to throw items? As far as i know health potions scrolls and cubes arent spells. I think that Deckard shouldnt have mana making him a special healer that has no cost but instead make his heals more complicated or increase cooldowns. And if youre going to leave him with mana at least make him gain mana back with some spells like make a gem for horadric cube which can return mana on the fourth talent choosing since there are some weak talents there. Let me know what yall think.