I get the idea that is kinda' like an anti-raven's cove. But just like Raven's Cove - once the quest is done, why would you ever come back? And Raven's Cove does have that problem. Unless you want to go and kills ghosts - there's nothing else to do there once you get done.

If Isla de Paradiso was a target for invasions that would work. If the island and several merchants carrying harder to find or more expensive items - that would work.

Or, if you want to really go the other way - then a similar idea to Raven's Cove where the island is a paradise by day but Hell after dark. And that could be the story. Say Jolly Roger was trying out the Muertos Moon Curse but on Paradiso it's a full moon EVERY NIGHT! That would be nuts...