The latest expansion pack has been released. Now, certain things are clear.

just because people are playing it doesn't mean there's a good atmosphere...
they feel "forced" to play because there aren't any other (new) installments, the old ones have been completed (and usually only have online play), and there are some interesting new features in the 5th game, so they want to see and play it... even if the graphics aren't great, and a lot has been taken from other games (races), and there are few objects (art and so on), that doesn't necessarily mean that everything else is poorly done...