It's already proven to bring people together. It's amazing fighting it in groups. I'd love to see it kept in but as some kind of Raid that randomly appears on the map every few hours rather than just a random encounter like the Kraken.
Maybe every few hours there's a point on the map where it can be summoned, so you must go there, play Merrick's shanty to summon it, beat it and you get some major loot that floats up. 5 people required to summon it should be kept in.
Obviously the issue here would be the complete war that would happen between ships once the creature is defeated, but maybe there's a way it could work and rewards are split.
