The more realistic the better. Swear-free worlds that are supposed to be full of criminals are not really convincing.
Elite does an interesting balancing act here, because the gameplay about flying space ships, also space fighting, exploring worlds, astronomy and all that are surely topics for most ages, while the world it is set in isn't reduced to the part that is okay for kids, but wants to be complete.
I am not doing much combat in Elite, and when I do I never managed to take the npcs serious because they kinda talk like cartoon villains. While the stories the game tells can be pretty bitter, looking at Generation ships and INRA bases for example, people living in this world are really much too polite and tame.
That said, I'd really love the game's NPCs to be a little more authentic. You always notice when you're in an environment made to be okay for kids, and that's certainly the case in Elite. Apart from that it's good I don't get to interact with many NPCs anyway and thus don't care too much. Swearing pirates who convince me that they are really mean dirtbags would be lovely though.
