QFT - It can't be said enough. If you don't know your teammates and IF this game had built in VOIP, imagine how much better it would be? I don't know JimmyBlueShoes the gunslinger. I don't know his play style, his skills, his strengths or weaknesses. HOWEVER, if he starts talking and I'm listening or vice versa, we've summed up a going part of it right there. NOT EVEN COUNTING the speed of voice over typing or the fact that we can keep fighting instead of typing.
The OPS chat is bad enough sometimes to the point that it actually turns me away from PvPing because of the crap that gets said in it. Give some of these players a VOIP to the PuG team mates would be even worse and if you think new PvPers have a bad experience now, just imagine what it would be like having 3, 4, or 7 other people cussing you out because you didn't know that there was a "throw" icon for Huttball.
Not saying that there were times that it would have come in handy, but you have to realize for it to actually work your team mates have to be willing to listen and if they aren't going to come running when you type out "west 2" it is doubtful that they will come running if you call it out over voice. If they do come, they would have come anyway.
If your team can PVP with no voice, great. If you've been playing together for a while and just "know" where your team is going to be, kudos. That's approx 0% of the PUGs out there.
A team doesn't have to be playing together for awhile to "know" anything. What it takes is situational awareness on the part of those players on the team. I have been part of numerous PuG teams that demonstrated outstanding situational awareness where the players shifted to a new location because they knew it was going to be attacked next.