I once supported this idea. Until I started using a microphone in COD4. While it is useful sometimes when there are people who actually use it to say whats going on and to warn you about snipers or whatnot, almost 90% of the people using it are either shouting into their mics with <12 year old voices complete gibberish that is in no way conducive to gaming, or they have their mic senistivity through the roof and if one hair moves suddenly their mic plays really loud static. Or even worse when the mic starts picking up on the voice chat and replays everything, except louder and more crackley. And then you have the people who replay the replays and it goes onto this huge noise thing that is so annoying and distracting that it causes you to throw the headset across the room at this time. Of course now that you have done this you dont hear they only compitent teammate yelling at you that there is a guy behind you and suddenly you are knifed in the head.
TL;DR = Mics suck.