I would like to see a system integrated into the multiplayer mission menu that would allow my friends to join a private lobby so everyone i want to play with can join my game with me at the same time without having to worry about how full the game is or if some of your friends will not be able to join cause the game is filled after 2 people join. i would relate what im discribing to call of duty black ops they have a system like this and it allows you to join any mission/map with all your friends, and theres no guessing if the game is full already. i would also like to see them put in system link and offline co-op/split screen so you dont have to be online to play with your friends.
There's a dozen threads on here that will agree there needs to be some sort of multiplayer or party lobby. But having an offline co-op or system link option is usually something that needs to be thought of up front. It's a major redesign if it wasn't given the foresight, I can't think of a game that has ever implemented it after a release off the top of my head.