I have no problem with Brutes, but they really need an upgrade to their intelligence and behavior. In Halo 2 they were basically damage sponges. In Halo 3 they were weaker, weirder copies of Elites. In Halo Reach they were annoying monkeys who didn’t really have a function in gameplay other than to use armor lock and wear stupid helmets which prevented headshots.
Sadly, I think Halo 2’s damage sponge Brutes were actually the most interesting to fight - at least they offered variety in enemy behavior, and provided a nice contrast to the Elites.
In the Halo 3 vidoc, Et Tu Brute, some animations for Brutes were depicted that in the end were never used. Brutes did some more in-character, brutal, interesting stuff like ripping a marine’s arms out, tackling a marine into a vehicle, and their pack mentality gameplay was highlighted. In Halo 3, they did no such thing, and their pack mentality was a disappointment.
To work in Halo 4, Brutes should display a more interesting pack mentality - protecting Chieftains, coordinating fire, different roles being subservient to each other, etc. Their berserk mode, which was absent in Halo Reach, should return. I think they should display more brutal combat moves - like taking human shields, throwing dead bodies at you, and of course, CQC. I think Brutes should not have shields, and instead their helmets from Reach should return. Their CQC should work like this - instead of powerful single blows like Elites, Brutes should charge in and use faster attacks - comparable to melee combos, they just keep spamming melee attacks which individually do less damage than Elite melees, but overall do more damage due to their faster, unrelentless melees.
During berserk mode, their melee attacks should knock you back a considerable degree. I hope that their vehicles and weapons in Halo 4 will provide contrast to Elite equipment - it would be nice if every single Brute weapon had a blade/bayonet on it and had its own unique assassination animation.
That way, Brutes should fit into their own individual niches rather than being weaker versions of Elites. All other enemies already have their own niche - the fast, agile Elites who are the only enemies who dual-wield and use jetpacks, the “tank” Hunters with their shields, the Drones who fly in swarms and land on walls, the Grunts who are cannon fodder, the Jackals with shields and fragile but accurate snipers and the Skirmishers who are ninjas/glass cannons with their agility and speed but lack of health.