What makes you think that a computer that can generate music cannot also generate a background for the "creator" of that music? It can give you all the stories that touch our hearts even more so than we can imagine.
Given two stories, both identical, where one story is real - the real story will always be more meaningful because it has actually happened within the constraints of our reality, granting it validity and us the ability to relate to it.
Now, consider two stories, both identical, where one story is "real" and the other story is from a simulated universe. Now I'd say that both stories are of possibly equivalent value, since both have happened.
I wonder, if they can compose, how long until passable lyrics are added along?