Modern is the last time/area you visit in MySims Invasion. It is home of MorcuCorp, so they have many employees. Many of the resedents here are unhappy because of MorcuCorp. You used to live here, before Morcubus sent you to the Future.
As said before, Modern is MorcuCorp's base, so they take very high notice of it. They also try to kick you out.