wait... characters can't be moved between servers? (what's the difference anyway)
and... haven't they heard of auto-logins/saved pw?
The main differences between the servers are the number of players, and the timezone (origin) of said players. Some of them were american, and some of them were european, and a large amount of these people have carried over. This means that prime time will be different for different servers, as well as dealing with different groups of people.