Going completely off the Marvel Cinematic Universe Thanos motivation here, which is different, canonically, from that of comic book Thanos; the latter sought out the death of multiple trillions of beings as a "token of love" of sorts to Mistress Death, while the former had the arguably more logic-based reason of culling the populace to ensure proper amounts of resources for those who survived.
However, if this was the case... why did he not just use the Gauntlet to double, or even triple the various resources in the cosmos to better suit the population?
We have seen that the Space and Power Stones can reduce the time something needs to multiply, or increase the potency of both organic and inorganic items, respectively. The Reality Stone could essentially have been used to fix the problem outright; considering that it allows the user to basically bend reality to fulfill their wishes, even if the wish is "in direct contradiction with scientific laws, and do things that would normally be impossible," that Stone alone could have taken dead matter throughout the universe and turned it into food, water, or any other resources any planet needed.
Need for conflict aside, why was this never addressed in the story?
Furthermore, if Thanos' ultimate goal was harmony throughout the universe, and he is the overall genius, why didn't this occur to him when he had all the Stones? Was this at all touched upon in the movies, and thus set as a "limitation" of the Stones in some way?