.wingman gameid should not only highlight your selected wingman, it should setup as asked for, a third vox channel.
It was asked for a long long time ago, and keeps popping up.
As to why, well I don't know about you, but when I'm flying an FSO frame, and I've got 1 channel set to squad, range is full of chatter from other squads, having that third wingman channel can make the difference between living and dieing.
Or you can run Ventrillo or teamspeak, but personally I'd rather have it in game, so I can look at my monitor if I'm in doubt as to who's speaking.