Nested in an article about Brutal Legend developer Double Fine counter-suing Activision in the ongoing legal battle is this claim:

Double Fine's suit claims Activision never showed interest in the game and canceled it in 2008 after it acquired Vivendi Universal Games. That was after an effort to convert the game into a "Guitar Hero" sequel failed, the suit claims.

I can imagine how those meetings went. "Can we make it so the lead character fights with one of our branded plastic Guitar Hero guitars? Also, we want to get a Tom Morello boss battle in there."

(Thanks Cubit and Mr. 8man.)