Because we should learn how to find the balance between ideal and material worlds. So if someone improves reality around himself, improves his thinks and minds, if he tries to do something good for this world he would have a chance to improve his reality. I think, that all things are connected : goodness and kindness in a soul bring goodnes and kindnes in our real, material life. Reality always answers us, we just have to learn how to ask it kindly :)