I have a son and daughter, ages 10 and 13. They're probably past the "little kid" stage, but I've been playing for about 8 years so they were "little" when I started.
I can see why some would be concerned about "bad" language, even though I've found it to be pretty rare that it's bad enough to be a concern, IMO anyway. I wear headphones, so it's never been an issue in my house.
Beyond that, I do find a certain irony in the idea that it isn't ok to allow a child to hear bad language, but it is apparantly ok for them to watch/participate in a game that simulates shooting/destroying/killing... Even if the kids just see "pops" shooting the "bad guys", is that really better than having them hear/learn/repeat a "bad" word?
Given the choice, standing back and looking at the two as seperate, we might be better off to switch the two around. Allow the kids to hear/speak the bad language, but get mad if they're exposed to a bunch of people simulating warfare.
It would also be inconsistent for me to get mad if they're exposed to bad language while I play the game, when they'll likely hear the same language at school, at the store, and/or while dad's out "fixing" the car or paying bills.
And actually, having my kids hear it while I'm playing might be for the better. At least that way it happens in a situation where I can explain why some people think it isn't "appropriate" and why I don't think they should use language like that. If it happens when I'm not around, I don't have that option...
And beyond that, I think there's a certain "regional" or "social class" difference in how/what language is considered "normal" or "offensive". In my normal day-day life, a lot of "bad" language is the "norm". To not use it would stick out as much as it would if I did use it in other situations. I almost speak a different language when I'm at home or out in public, or with my parents. In game, the language I use on private vox with friends can be radically different than the language I use on "range" vox, or on private vox with people I don't know very well. That could easily give people I don't know a much better opinion of me than I deserve. A kind of "language disguise", hehe!