And why is that? It's not because people don't like the idea of playing one country as long as possible: when start and end dates were hardcoded in the .exe, people cracked the .exe. It's because EU3 gets easier as your country gets larger, so that after 200 years of play your country has expanded to the point that there is no challenge any more. If it got harder to run your country as your country got larger (in some fun way as opposed to lots and lots of random rebellions), people would continue playing.