bring back population counters... Give us the tools to build our own game, not just our own maps. Provide an infrastructure to create lobbies for match making into our own games with our own parameters. I know, really dreaming here, but it takes 343 out of the loop of deciding what game mechanics to implement and we would not have to blame them for a bad halo experience.
I did post a thread addressing this on Waypoint. What I proposed was to limit Spartan abilities so they'd be more supportive, rather than aggressive. I'd limit sprint, so that it becomes a short burst of extra speed, rather than being an illusion that it is now, since it causes elongation of maps, where you get from A to B at roughly the same time you do in classic Halo.
I don't play MP, so I don't have anything to say about that, but I'd get more people on the Forge team. I love what Tom French is doing with Forge, but from what I hear, they don't give him enough dedicated people to work on it. Needs more people to help code & especially test new Forge features.
I would sacrifice a pure child, preferably white, to Moloch. This will lead to me gaining the powers of darkness. I will use this power to destroy Microsoft and 343. This will lead to the rights for Halo being up for grabs and since I gained the powers of darkness, I would be filthy rich and buy the name. Then enslave Bungie and anyone who was originally a part of the project to make the game. Then I will give Tom French the resources he needs to create an amazing custom experience. Then I will go to Hell.