Warner simply isn't "respectful of how much we've done to bring new audiences into the market," Activision CEO Bobby Kotick told the Financial Times.
"We're introducing a whole new group of artists to new audiences that is resulting in their iTunes downloads being exponentially higher than they would otherwise be, [as well as] new album sales and new merchandising opportunities," he explained.
Warner label Roadrunner, for example, noted a bump in DragonForce album sales after the band was exposed to a wider audience in Guitar Hero III.
"This is an entirely different business [than iTunes] that is very technically complex," concluded Kotick. "We're going to favor those publishers that recognize and appreciate how much we can add value to their artists."
Many Warner artists, including Avenged Sevenfold, DragonForce, Red Hot Chili Peppers, Linkin Park and R.E.M have songs in either current or upcoming Rock Band and Guitar Hero games.
Other artists that fall under the Warner Music Group umbrella include Led Zeppelin, The B-52's, Green Day, Depeche Mode, and Paris Hilton.
Rock Band and Guitar Hero were both created by Harmonix, acquired by MTV owner Viacom in 2006. Activision then bought Guitar Hero property owner RedOctane and assigned development of the guitar game to internal studio Neversoft, while Harmonix went on to develop the multi-instrument effort Rock Band.