If I wasn't playing World of Warcraft, I could totally imagine to play one of the other games out there. Lord of the Rings Online, for example, or Warhammer Online. So why am I playing WoW? One of the major reasons is that all of my friends are playing. That is called a network effect, games or services with a strong social component get more attractive the more people there are already using it. The downside of that is the negative network effect: The fewer people are playing, the less interesting a game becomes, with players quitting when their friends quit.
One game that suffers from that very much is Jottonia, a virtual country, a massive multiplayer nation simulation based around stock trading and related businesses. Besides stocktrading, players can become journalists, lawyers, or politicians, and might ultimately even be elected president. It's a bit like EVE Online without the space ships. Or the graphics, Jottonia is completely text-based. Jottonia used to have around 2,000 players, but now it is down to 240, with only 50 or 60 being active. In a game that has such strong elements of politics, it is hard for new players to make a place for themselves in a community full of veterans. You know how MMO players are, not always very helpful to newbies. But there is a newbie forum with an active moderator, Mr. GoodStuff, who is hoping to get the word out and revive the game if only more people would join.