no thank you.

for a properly done seafaring game, it needs to be done that way from the ground up. you cannot easily shoehorn that in to an existing game. not to mention, if the player is in a small ship, why would they be engaging in ship to ship combat? Or should they also be able to hire a pirate crew? maybe, get a spyglass even to examine distant objects and island?

mmos like FFxiv tend to be rather linear, since most people playing like having a set end goal. they also are not all fond of crafting, so this building a ship part may not fly as well as you think. either way, I dont see it as something viable since AC already does it.