No one's suggesting that SE should put in voice chat, you're right that would be horrible. However there are many options available to people on PCs for voice chat. Ventrillo, Teamspeak and Mumble are among the most popular for gaming. They are private servers where you can speak only to your group of friends. They even support separate channels so that no one room gets too big. It's extremely common these days for Linkshells to require people use one such system.