Really no surprise!
This was going to happen sooner or later.There are many causes for this.
1.Overstarcion:To many music games are out every year.
2.No real changes:You can say that 95% of music really have nothing new just new songs and you would be right.
3.Cost to much:We are in a recession people are not going to spend a 120 dollars for one game and they can get 2 for the same price.