Having world events in the game would not only create action by bringing a lot of the players of the map together but would also create situations you likely wouldn't experience otherwise.
When you have an objective in which for example 8 different crews share the same goal of completing, then the sea warfare becomes something else. Strategy will be different to all other battles you'd of had and the best pirate crew will inevitably always come on top.
To stick with the theme of the game, using changes in weather patterns or fore-shadowing from vendors at the outposts that will give long voyages to complete that will give a time and place to when the next event will occur. Having something like this will not only separate the wheat from the chaff but also make it so that the reward of the event is even sweeter or for those who don't become then victor, the next time will be ever more desirable.
This sort of thing doesn't need to be added into the game immediatly, as to let everyone have a feel for the game, but shouldn't be left too late as to keep the player base growing and interested.
Incorporate this with other things like Alliances and having these full-scale battles will create stories of chaos and enjoyment.
