I think now would be a good time to take a step back and for everyone to call the elephant and elephant. Younger players with high pitched voices aren't a problem with Xb Live. Younger and Older players alike have the same rights to gaming while some younger players should be monitored by their parents (just how I feel, my mom did that to me, the way ti goes).
Because its an environement where the consequences are very very light, younger players tend to say things that go beyond trash talking, but instead are hurtful and rash. Its a chance for them to act out. This is not a blanket statement. This does not apply to all younger players. What this is, is simple psychology. If you have a spot where you can do a behavior that's exciting and wrong with no consequence then there are going to be people that do that. There's also no way of seeing the person on the other side who 4 out of 5 times is probably just annoyed, but that 1 out of 5 is hurt.
That's not to say that adult gamers don't do this.
We all should respect each other as gamers and provide good experiences because of that respect. The people on this forum are very likely to be the people who have great public game experiences with each other. The people on this forum are probably the people who also get annoyed at racial or mean spirited things being said without remorse over xbox live.
When something is wrong, its wrong no matter what age. So to the younger gamers that don't fall into these lines, then keep doing what you're doing, you're representing your youth, your people well. To those adults who are annoyed and taking it out on every young gamer, that's wrong to do as well, but venting needs to happen sometimes, watch out for that gray line stuff; its hard to tell which side you're on sometimes.
Finally, live long and game hard and you'll find great sets of long term game buddies.