Making those things is easy. Giving them purpose is hard. If you have rain and night it's cool at first... then you realize there's no reason for it to be dark and making it harder to see, or have it rain that's distracting and loud. Then players ask for ways to disable them and then suddenly some players are playing in darkness(which is a handicap imo) and some aren't... so they disable it because it adds nothing to the game.