Party Up Feature

Maybe there should be a party up feature in the title update so when we meet players online and have fun, we can play with them in matchmaking without the trouble of inviting them

There is one already. It just works differently than Halo 3. Instead of pushing X to party up, you simply remain in the lobby and matchmaking will combine all players into a party.

Last time I checked you can party up with players, by not leaving the matchmaking lobby.

yeah but what if you dont want the other people and just want to play with the 3 other people

Its just easier to back out and invite them by pressing select and shows the carnage report of your last game played and invite the player.