Why is it such a pain to use items in combat?

Since I can “equip” and usable item to my “belt” and then use it in combat, why not just let me use it directly from inventory to scale down on all the clicking.

This is not as big hassle on pc since clickin with mouse it quick.

But on console using a controller this takes a long time and adds nothing but frustration to the game play.
I would understand if what you had on your belt starting combat is what you are stuck with, but since this is not the case why do it like this ?