Just because you want to restart 1,000,000 times going for a high score, doesn't mean coins are broken. They are absolutely pointless now, you get 5* you break even essential (yea you get -50 or +50 for gold coins whatever thats not the point its even) Playing a song with coins shouldn't net a win of coins at all. You should have to obtain them on naked runs (learning the song) or playing goals (on facebook OR added to the game itself would be awesome) Thats the challenge, thats the fun. Or winning through extra bonus, new song bonus, double coins weekends or whatever.
They have plenty of ways to get coins. Playing a song with coins shouldn't be a way to get coins.