How come the Arcane Archer gets access to more magic arrow types, but not more chances to use them each day? Was the other considered?

How come the Arcane Archer gets access to more magic arrow types, but not more chances to use them each day? Was the other considered? Idea was to keep them powerful – flat uses, but power increases, mainly to keep magnitude of effect relevant/noticeable

— Mike Mearls (@mikemearls) December 4, 2017