I still say keep it optional. Yes people can recognize their buddies voices but that's talking current tech, you think about the radios they're using and the range, it's lucky they can even understand each other. And besides 0 channel spam won't stop, it's the nature of the noobs in game.
Yes clearly 200 years from now they will have worse radios than now, radio's are high tech sci fi gadgetry and not something that has been around over 100 years.