The reason why none of the iconic or newest weapons in Halo aren’t in the game is that they are a standard insta-kill, no brainer, no skill ceiling or weapon clones. Weapons like the brute shot were easy no brainer weapons to use, the mauler was just as bad as an Assault rifle in H3, the Railgun was an insta, the spartan laser had a laser pointer but people will just play peekaboo at the last second to hide it and make it pointless.Same can be said for many weapons---- The energy sword and grav hammer made it because they changed some functions. The energy sword cant swing until its fully taken out of and the grave hammer has a full wind up to give those two some unique edge, in my theory to justify why they are in the game.
And listen, Im not against these weapons coming back. But this is just how it is honestly and truthfully seen. You can personally like a specific weapon but if it doesn’t make the cut then 343i believes it wasn’t necessary or will break the gameplay sandbox.
I just personally want to shed my insight on my theory on why many weapons aren’t in the game. It can also be them adding it in the future, but currently, everything in the game works because they each have some form of skill ceiling used in special ways now from being a primary kill weapon, a support weapon or a utility weapon (anti-air, sieging, defending, etc)