Yeah, because if its limited uses, I will most likely end up not using it at all. I'll always be saving him for an emergency that will never come.
Even so, having a limitless number if Karstaags available (even restricted to once a week) would be obscenely over powered.
this
his absurd power pretty much requires a limited finite number of summons
i tested him out on alduin in the vanilla mq's final fight
alduin might as well have been a garden lizard going up against the death star
a summon that strong isnt really needed
by this point in the game, most are practically gods in human form anyways