For me its more of convenience. Ofcourse there could be a better command for nintools too but id see it being a bit more complicated, something like /stock "item". But with a /ammo command it would just tell you what ammo you have equipped, without needing the context for the ammo. For me its not a "What if i run out, then i need to pop a new macro or go to my menu!" as much as those few times ive popped barrage with 2-3 bolts/bullets/arrows left and wondered "wtf, why didnt i get the damage/tp i was expecting!?"

Dont get me wrong, id be all for one for nintools and other items like cards for cor, but i see it being easier to implement for ammo specifically.