Brutes were tough as hell in previous Halo games, and according to the game's lore, they were also members of the Covenant. As such, it comes as no surprise that they won't be showing up in the upcoming Halo 4, which is more focused on Promethean enemies and a small smattering of renegade Covenant forces.
Halo 4's franchise development director Frank O'Connor told readers at NeoGAF that they won't have to face any annoying Brutes in the upcoming game.
A fan asked him directly: "Just tell us if Brutes are in Halo 4 or not," he responded: "They are not – but there's some story stuff I can't get into."
O'Connor did not clarify why they wouldn't be present in the game, but we can pretty easily deduce the reasons for their absence.
That said, Gravity Hammers have confirmed to be in the game, but characters apart from Brutes will be the ones wielding them this time around.