[Jourin]

Let us take a tiny non breatheable planet with 50% production. You don't get any population bonus so it will only produce 400 minerals. That 400 is one shot each turn. Use it or loose it. Instead build a storage facility and store the extra production from a good production planet. In one game turn you use up all your production and can't start any new build. Next turn you have excess production so you loose. The purpose of storage is to maximize resources.

Reseach and Intelligence get the same bonus for population and happiness. A larger planet will also have more population and usually higher happiness thus more research per buck then a single research compond on that tiny moon. Try build some storage locations and see how much it helps you.