I agree. If it is feasible there should be one main server for all because this small amount of players sprinkled across these servers really takes a way the potential for a truly living world.
I don't mean to be a downer here, but this game as much as I personally love it, and likely so does everyone who posts on these forums. But the game has a very limited market of individuals because the age of sail does not appeal to everyone, and the long sailing times between place to place would be a turn off to others as well. In short there is a niche market for this game. Why is this an important factor? Because the amount of people is quite limited (it will grow, but only gradually), so splitting this already limited base across all servers will affect everyone through times of inactivity.
You need a large player base to keep PvP going, you need a large player base to keep the economy running and prices competitive. So the best course of action (if feasible with hardware and network) is to keep the maximum amount of players together on one server.