I was thinking that for the Halos 1-3 there should be a feature that would enable the previous games to function more like 3, for instance, in Halo 2, Brute infection forms, and for previous Halos live infections and infections of dead bodies. Guns not previously in the game, or removed from newer games, would all be available, duel wielding in Halo CE, etc, features to be added across all the original titles. Obviously it should be a setting and not an outright change, as that would upset many fans.
Feel free to use the MCC feedback threads.