I like the voice commands. It really is like some sort of primitive form of communication. A few people will come up with a plan via chat messages, then go someplace and defend the area.
One or two people (the planners, from the chat) say "Stand your ground!" like in Phazey's example. Soon everybody's shouting the same thing like a bunch of seagulls. There's no better way to let everybody know what to do than to have half the team scream the same thing over and over again. It's a good way of getting a gauge of a group's agreement/disagreement of a strategy.
Plus it's awesome to be defending a spot (everybody screaming "Stand your ground!"), then all of a sudden, at the right moment, I rush foward screaming "Attack!" in a high-pitched, nasely voice. My team echoes my voice command, and I know they're in agreement. Then we all rush out and die.