Random mw2 gamechat/party chat question?

I was thinking earlyer, you know how on the xbox how you have to be in game chat if you are talking to friends in the party to play anything but mercenary/ffa/ground war? What's the purpose of that anyways. as we already know from cod4 gamechat is only used to trash talk other players and brag about skill and amazing kills/random crap that has nothing related to the game so what was the point of making us do that in modern warfare 2? Was it to help the team? I never see that happen when i am on as much as just randomly singing/cussing and dissing other players/bragging about kills/arguing which is mostly what goes on durring gamechat. also if anyone knows how to byp this (besides private chat i know that one already) please tell me its anoying as crap and i see no point in it due to that no body uses teamwork/tactics anyways so i highly doubt anyone helps teamates talking through mics even if people did think of plans for the match instead of making it up as it happens.