I suspect the 5E rules were made with computer games in mind. This was likely not the case with the previous rule sets. For example, in NWN during the end battle my mage ran out of spells and charged items, and so had to resort to beating the end-boss with a club. It took a while to do that, and as you can imagine, it was not a satisfyingly splendid display of the finest magery. BioWare thanked me for my my feedback, and noted that it was good that I used all my items. One can never know for certain, but I believe my story is the basis for the unlimited/repeatable use of cantrips in 5E, so that wizards will never again have to resort to beating the end-boss with a club.
