I would like to be able to mute certain players but still be able to see what they type.
One great reason for this is for families who play (we are a two pay-to-play-account household): I don't need to hear my wife's voice in person, then a second later hear the same words again over my speakers. However I would still like to see anything she types. I know other multiple-player families that would appreciate this also.
Another is people who come across incredibly loud; I've even had some people that I thought were incredibly loud and other players thought their voice was fine. Even better than muting would be a setting from 0.00 to 1.00 per player, and of course make this a limited size list.
Edit: If you had a volume setting per player, make something in the middle, such as 0.50, correspond to the current setting, 0.00 would mute, 1.00 might be double.