A day and night system wouldn't really add any benefits , it would cause issues since not everyone would want day and night system and if there was an option to disable it some players would be at a possible disadvantage due to brightness levels which would temper with the balance of the game. We have animal pets in our houses , considering we can already buy pets adding animal would be a bit weird unless it came as a small part of a big update witch isn't really worth the effort in my opinion