I am right there with you. I use a mod, currently, in order to have a Rock Star. I have since re-imagined my stories about him. I began a new save taking him all the way back to his infancy. I thought it might be fun to see how this future Global Superstar, Unstoppable Rock Star, came to be.
New music would be a very nice addition. The mod allows me to watch him in action on the stage. This Sim first became a Rock Star in Sims 3. I miss the songs from the Superstar EP, big time. "Maybe It's Better This Way" is how Erik closed his Show. "One More Grey Day" and "It Hurts Both Ways" "Freeing Myself" I actually created lyrics in English for. I would also be pleased if the 2001 song, "Fall Into Me" could be incorporated, among others.
I also miss some of the dancing/moves he would make in Sims 3.