What is the purpose of decorating the rooms with the colors?

It is fun! Just for pleasure sake. Then when you are done decorating a room it will take a “Polaroid” snap shot. Then you can view your pretty collection of rooms. I had more fun switching out the colors and trying different combos when decorating. Once you have spent your 2 lotus flowers to decorate something, you can go back and change it for free. However once the whole room is done and you take the snapshot, you can’t change anything.