Traditional MMO's are persistent worlds. But Players are only Semi-Persistent. We have to do Real Life.
This means traditional MMO's are always seeing a flux of players entering and leaving, and the likelihood of you seeing the same players consistently is diminished.
Also, when events happen, they have to last days or weeks to make sure everybody has a chance to take advantage of them.
I propose Semi-Persistent MMO's.
Imagine upon entering your new MMO, you discover a list of servers which are not only organized by time zone and population, but also by play schedules.
You could choose a server that only plays Tuesdays and Thursdays from 9 to midnight for example. But there would also be some that play from 8pm to 2am every day of the week. Or even morning servers. If you wanted to play even MORE you could play on multiple servers with different schedules.
Just think...In a world where ALL players are present every time the game is running, you could create consistent rivalries, and player-made factions. In-game events could happen every night. Nobody on the server would miss an event.
Sports teams and clubs have operated this way forever. Why not run a server this way?