I'm going to have to disagree with you. I have felt that with H5 beta, each of those guns really has a distinct role in the sandbox, possibly for the first time in the Halo series. Each gun has its ideal use scenario and tends to prevail when employed appropriately. In order of efficacy from closest to longest range, you have SMG, AR, Pistol, BR, and DMR with just the right amount of overlap between each (note that the starting weapons fall right in the middle). Picking the right weapon for an encounter (or picking the right encounter for your weapon) is essential in this game.
I've been really enjoying how it's not just a race to pick up BR and use it exclusively, but rather a game of adapting to the weapons at hand. This is a good sandbox.