Every magazine and every book they publish contains a picture of 'paradise' - it is usually among the very first paragraphs used to 'hook' it's victims. It keeps the earth - something they can touch and smell every day - part and parcel with 'true worship'. It is the medium that they have selected to paint thier doctrinal canvas.
Indeed, its already been said that its the main carrot they use to get members biting; its quite a powerful tool to be honest - like above its easier to believe in something intangible when you have something you can visualise or touch. They would be committing commercial suicide if they dropped this doctrine.
Gary