Metallica drummer Lars Ulrich recently told KBS Radio why the band decided to offer its music on Guitar Hero while denying it to Rock Band. Ulrich's somewhat cryptic reasoning: "We had to make a decision, and it was one or the other, and we felt that Guitar Hero were more suited for what we were looking for. They were ready to step up on a number of fronts and it's been great." Ulrich did not elaborate on how exactly Activision "stepped up," though he does mention the rumors of a Metallica themed Guitar Hero. Ulrich did not confirm such a game was in the works, instead saying "who knows what's gonna lurk next year, but it's pretty exciting."
So, Activision stepped up and Guitar Hero was more suited to what Metallica was looking for. Somehow we get the feeling that Activision stepped up with a suitcase full of money, which is exactly what Metallica was looking for.