I've tried to see if this has been brought up before, but couldn't find it.:
The in-game voice chat, as well as the text chat, currently allows dead players to talk to players that are still alive. This leads to awkward situations, e.g. where some "dead" teenager is screaming in my ear that an enemy is just around the corner about to kill me. It completely removes the thrill of playing a tactical game like this. It needs to be fixed.