Was just thinking (painful, I know...) about naming sims, and sometimes for the sake of immersion, I set them up as titled (nobility) individuals, thereby setting up a dynasty for royalty. For instanc...
That would be interesting (and it'd open the possibility of a similar field for middle names).
The question is only, what occasions the game would use the full name and when it would only use the first (or first and last). That's where it might get complicated.