http://xkcd.com/331/ <- This
Sometimes, we somehow don't believe reality because it doesn't seems real. If you try to simulate it in a game or something then people won't feel like it's real either!
It's the case with the night sky there, I think, they probably tried to do something similar to what a city person would see (I can say that there is still far more stars in the LL screenshot than I ever saw even the middle-of-nowhere city I spent two years at!).
Also hidden somewhere there might also be the "Let's not put a far too complex/high quality backdrop in the sky because of performance issues" situation, there's a reason we got FoV and sadly a really realistic sky would kind of push things in my opinion :(