Look, I'm back from travelling!
To answer your question, choosing the number of servers is a rather complicated issue. It's based on pre-sales, opening crunch (when people play a higher percentage of the time), and so on. Basically, you have to have a bit more capacity than you're expecting for your opening, otherwise people have poor performance, but you run the risk of having more capacity than you need, which results in lower populations than you want.
We currently have the latter. There are two servers that are really lighter than we want: Bellamy (which is extremely low) and Hornigold (which is low). The rest of the servers are reasonable with varying populations. It's not a surprise why Bellamy is low: our rollout in Spain has been non-existent, with players not able to find the games on the shelf and virtually no advertising. I'm still digging into exactly what's going on there and to see what we're going to do moving forward for this territory, but until we get that addressed, we're going to be extremely light on Bellamy. If I had to do it all over again, I'd a) do the Spanish rollout correctly at launch time (preferrable solution) or b) reduce the servers by two.
As for what we're doing in light of the above, we're going to find out what the issue with the Spanish rollout is and address it. Bellamy really needs that rollout.
As for the rest of the server populations, we're not looking at making any changes in the near term. The reason for this is that our sales have been a continuous, straight line for the last three weeks, so we're adding people at a pretty good clip. Nobody knows, of course, how long that line will remain straight, which means we don't know what our initial population is until it starts to taper off. In the meantime, as we're adding people which increases concurrency, we're also reducing concurrency because people play a crazy amount when the game starts. After a while, they move to a more normal playtime. Which means that there's a smaller concurrency from the same level of subscribers, so the growth of subscribers is offset a bit by this.
People ask about this in the context of PvP, because, of course, you want people to play with. There are two elements that reduce PvP which are unrelated, but exacerbate the issue. First, people are trained by other games not to PvP until they hit level 50. We're very unusual in that you can PvP from level 5 onwards! I was just looking at the graph today, and of course, most people aren't at level 50 yet, so they're not inclined to PvP. There's really nothing we can about this (we've tried education, but it's hard to reach everyone) but it's a problem that rectifies itself naturally.
Second, our risk vs. reward structure dis-incents people to play PvP. We're all in agreement that this is true, and we're working on the changes we need to make to correctly incent people to PvP. We'll announce more on this over the next week as we talk about the 1.2 patch. Keep an eye out for the dev log.
Finally, if you're interested in how we think we're doing, well, just fine thanks. There are things we'd like to improve, but the reception of the game has been really good, for both players and the press, and our numbers are good. We have some new hires to announce, and some exciting overseas news that we'll be announcing soon.