With 19 XIV servers running (i.e. when they have electricity) and, what, 35k people playing, why are we not seeing servers merging?
Here are a few reasons for it that I can think of off the top of my head:
1) Once XIV goes PS3, there will be a large gap between PS3 and PC players - by merging you can have the PS3 users start fresh with their own peers while we continue on with our own peers
2) Keep current XIV players happy - we'd be playing in well populated worlds
As a result of (2), we'd be able to:
A) Find groups
B) Establish [friendly] rivalries between guilds for NMs, items, etc
C) Find a LS that fits us well (social vs core vs German vs Japanese, etc)
D) Feel like we're playing an MMO and not a single person RPG
E) RP, for those who are into that
3) RL gil - it'd be cheaper to run fewer servers
Mostly though, it's point no. 3 that I feel is the most important (to SE). Frankly, I'm surprised why it hasn't happened already.
I also think that the fact that all these servers are running is a sign of SE's misplaced optimism. It's like they're waiting for the servers to fill up, even though it might take a while (if ever?).
Finally, I realize that there are many inactive accounts, but 19 servers still seem like too many.