I find that you need to be proactive about teamwork in BF:BC and you get good squads.
I'm often the first person to use voice in my squad, but within 3 minutes two others are using VO as well . Intel like "incoming from river right" work very well in the linear gold crate gametype and you don't need to use or ever own a mic to benefit.
Last night was very similar to what I describe above. I was experimenting with the Genghis Khan tactic of mining a road, running up and blasting rockets at armor, then fleeing into the mines. 4 out of 5 times the tank just busts right into them. This time I had a friendly APC semi-supporting me, who was completely outclassed by this battle tank I was trying to trick. I told the guy over voice to back up instead of trying to paper cut him to death, and damn if he didn't reverse. The t-whatever comes over the hill, fireballs, getting me 30 points. For the first time in the game, the guy in the APC uses his mic, saying "Dumbass".
Now we "e-friends". Once you start winning, teamwork increases dramatically.