I have noticed that in the game since I was first in the insider program not a whole lot more enemies have been added to give some variety.
I think even adding NPC ships with living crews would be good just to mix it up a little and maybe meeting ships you can trade items with at events in the ocean.
I also think some newly developed islands would be nice with say a large town or city centre for other pirates to meet and create alliances for specific missions.
Sort of like a safe zone, not to unload cargo but to give the option to easily make and coordinate missions that need to be done with other crews.