First of all, I think you missed my main point; THIS IS SOCOM WE'RE TALKING ABOUT! Not Warhawk. As fun as Warhawk may be, it didn't before release (duh) and doesn't currently have a following the way Socom does. So that gets man, many people to purchase the mic bundle right there. Second, who's to say a different headset wouldn't be chosen for the Scom bundle?
Oh, and something else important worth noting: In Warhawk you have to hold L3 in order to talk. This is a real bother and I think, as a result, there are fewer people speaking while playing in an online game than if it was easier to chat. Other than that, Warhawk, in it's current form anyway, isn't exactly set up in a way that puts a focus on real communication and teamwork.
Get what I'm saying now?