World is full

[Fourtoes]

timezones, and in general varied playtimes, there is also the fact that people are extremely concetrated to a few areas atm

This just seems like a statement you didn't think out thoroughly. No matter the timezone, or the playtime, or the fact that people are concentrated in a few areas, there should always be a spot for you to log into your world.

An analogy I can use is:

Would a movie theater sell more tickets than they have seats available? No they wouldn't, they would put up a SOLD OUT notification.

Square definitely put up a "SOLD OUT" notification by locking new player creation, but they forgot to up the limit of players online at one time. That should always match the number of players created on that world, to ensure they can always log in to play.