Like one person in here said, I would like to see some "Infiltration" type gameplay (Fight from A to B, defend B, fight back to A).
A sort of "level match" system would be nice. So I could get put in games with players around my level (60-something), so I'm not in with people playing their very first MP match.
I also like the idea someone mentioned about "categorizing" the random drop packs into Weapon Upgrades, Equipment, Characters, etc. packs. I never use shotguns in MP, since I prefer to hang back and shoot from a distance. So why do I keep getting new shotguns or upgrades for them that I'll never use? My preferred weapon is the assault rifle. I have received a new weapon for every slot except the assault rifle. I have 2 sniper rifles, 3 SMGs, 4 shotguns, 2 pistols, and 1 assault rifle. Though, my M-8 Avenger is level 6 now so I can't really complain. Also, give me customization options for the other races, not just humans. My Drell and Turian characters are looking pretty bland.