I have a suggesting for Goals which I am surprised that they are not in the game.
Expert Level Goals. We already have Easy/Medium/Hard but having Expert Level Goals which have a significant coin payout. Like Powerup Goals that require points from 2 powerups rather than just one. Or an Advanced Rock Band 1/2 Throwaback Challenge that requires you to Gold Star every song rather than 4* but gives you 100,000 coins for completion. Or Goals that have you GS difficult albums like Megadeth's Rust In Peaces. Right now I don't have a reason to play goals because I can't get any sense of accomplishment because every goal is just downright too easy. The only goal that was remotely challenging is the Metal Facemelter and only because it had you GS Holy Wars when the game was first out.
I wouldn't mind goals that only about 5% of the players could ever achieve. They are completely optional and would give the hardcore players something more to do. A goal should be a barrier and a challenge on how to overcome it, not a simple checklist or an excuse to play a song.