I have a good friend who is one of the greatest songwriters on earth. It's a crying shame that hardly anyone outside of Memphis, TN, has ever heard of him. But he and I used to play in a band together, and I would often tell him about the crazy dreams I have every night. He would just be amazed at the lucid weirdness in my dreams, and that I could remember them so vividly. He said that he dreamed of the most boring things in life, like filing or washing the dishes.
So here is my theory, and I could be wrong (but I'm not). Those lucky souls we call artists do not need to be so creative in their dreams if they are putting all their creative energy into their art. Those of us who work real jobs and seldom do anything creative, but who were actually supposed to be artists of some sort -- we are the ones who have these crazy dreams.