Nothing much would change for you then if it was added. Turn down the voice volume to 0, or utilize the mute button on the occasional annoying person. The vast majority of players would appreciate such a feature in an inherently teamwork based game, even if at worst, they found themselves communicating with only a few people on the team.
How it is currently:
EVERYBODY FLAME RUSH! You might get 1 or 2 people to help you out most of the time, if that. Most people on your team won't notice the text over the action.
Now imagine hearing the same thing over voicecomm, and suddenly much of your team is responding, and working together much quicker simply because of the ease of communication. How many scenarios can you think of that would be instantly improved just by quickly chatting with your teammates with voice?