Well for starters that lets out anyone who is hearing impaired in any way. And yes we do have a few of those ingame. Worked with one just the other day. Nice guy, good pilot, quick learner, but can't do voice.
For seconds, on FSO nights when you get 25 or so guys all on 1 vox channel, and another 50 + on range. Sometimes its nice to be able to just send a check 6 without having to try to get through on vox.
What I wouldn't mind seeing, make it a check box if you want to receive them or not.