I prefer text only for in-game communication with strangers.
Reasons why:
1) Salty gamers who troll to cope with their IRL issues would use it to insult others that much faster
2) do we really want to hear other people breathing into their mics/doing private things when we don't know them at all and are just trying to get our dailies done
3) If you are a female gamer, the likelihood of harassment goes way, way up the second a male gamer whom you do not know can identify your IRL gender. I barely tolerate that from FC mates and guys I know (usually I snarl at them, actually), so the idea of strangers pulling that nonsense makes me want to hack their computers, find their locations, travel there, and set them on fire.
4) Related, if you're a female gamer and you're the tank, the likelihood of some male gamer deciding you don't know what you're doing and either trying to lecture you how to play or just ignoring your directions goes way, way up. Yeah, that's a thing.
5) people annoy me in general, I don't want to hear them
6) social anxiety
7) you can't record it if someone is verbally abusing you, making it impossible for GMs to help you if this type of behavior is going on
8) people talking makes it hard for me to concentrate if I can't completely ignore them