Highly unrealistic suggestion and almost certain that its not going to happen, but if it were up to me..
Multiplayer back to CE/2/3 format. No perks, boost, apples, bananas, no prematch bull**** that gives you certain advantages over others. The power of halo's multiplayer was that it was stripped down to the core of what multiplayer is. The battles got decided by skill and map knowledge alone. Everyone has equal opportunities to dominate a game. The best player were...the best players.
Those random ordnace drops are also infuriating. They make no sense at all. The only reason why this was brought to the table was probably to make it more easier to come back when you and your team face a better opponent. But the whole point of facing better opponents is that you try to become equally good if not better by playing a lot and understanding the game to it's core. Not because you've been given a SAW at random.