So what if random, ominous, creepy things were added to the game that only a select few pirates could see. For instance let's say a pirate goes to an uncharted island that has a book which tells the pirate clues to go to another island in order to reach some sort of secret. This place would only be available to a certain amount of pirates. Thousand maybe? (or more or less) This would create theories and "Tall Tales", but from the actual players! If these "Tall Tales" get popular (and interesting) it would create something new that the community can get excited about. This would therefore allow new content that the players directly made themselves is a way. But these tales would have to fit in with the SoT lore, so theres also that.
Remember, just a suggestion. :)