I remember playing Everquest 2 soon after release. All players were in the lowest levels and of course the newbie zones were crowded, oh man, they were!
But coming from the experience from the first EQ, the developers implemented a system that would duplicate a zone in more istances and shatter the players population between them. So, entering Queynos Harbor for example, you were offered the choice to enter Queynos Harbor 1, Queynos Harbor 2 and so on, or any random instance, so that you could still reach your friends in the same area but without making the place too crowded.

This idea also solved some of the issues present in the first Everquest where, in some very popular zones like the trials ones, you had to wait your turn to enter and fight your preferred named bosses. Not very fun and immersive I must say.

But what about now? Why the "choose your istance" window is so rare?

PLAYING TIME
If you ever had the experience of playing a MMORPG soon after the release date, you know that since everybody is new and the players interest in the game is at one of its peaks, most of them use to play more than usual.
That's not very scientific but come on, imagine yourself with the brand new game box in your hands, the client software just installed on your home PC, can you logout?

Really, can you logout?

Eh eh eh, I bet you can't, you can tell me what you want
Well, don't worry, it's not only you. This is one of the reasons why servers are most full at release than later, even compared at the same number of active accounts.


DIFFERENT LEVELS, DIFFERENT ZONES
Another thing to take into consideration is that at release all players are low level, and so they are concentrated in the newbie zones. Currently most of the Everquest 2 servers population consist in high level players, but lots of low and medium levels also exists.
This means again that player characters are now shattered in different parts of the big world.


HOW MANY ZONES YOU SAY?
369 zones.
Ah no, that was at release, but now we are at more than six hundreds.
What I love about Everquest 2 it the amount of new content (both free and pay to play) that is regularly released to the public. I do not have to explain how, when the world gets bigger, the population becomes more and more sparse.

PVP SERVERS
Last thing to take into consideration is that five new servers will be opened after the release of the expansion "Kingdom of Sky". These servers will host a PvP ruleset and most probably take out population from the existing ones.

SOLUTION
So, basically this is why I believe in Scott Hartsman, Senior Producer of EverQuest II, when he says that the server merge is not caused by players closing their accounts.
Yes, server merge. That's the idea, and in my opinion that's a good one!

Travelling in a too crowded world, when you are in very dungereous zones, doesn't makes you feel like you are really adventuring, but usually empty towns and generally empty zones kills the multiplayer feeling from a game, and this is also to be tought about the PvP servers, since nothing is as much boring as combat with no enemies.

The mechanics of this server merge are explained in this Producer letter :
Read it if you don't want to loose your friends, if you have preferences on wich server to move to. If you don't, well, in a couple of weeks you will just enjoy more eople to play with.