What if in the next Destiny you had to collect the ghost and take them to a library in the tower. Once you take them the librarian then has to decipher the ghost and extract the data. That way next time you come back you have a text log or audio log from the ghost that you can read or listen too. They can be about the guardian they were with or an enemy they saw or even treasures that they were destined to get. It can be told from the ghost or maybe the guardian left a message in him. Maybe some of the ghosts could lead you on a small side quest to kill the enemy that killed the guardian. Or look for the lost treasure they were trying to find. But instead of telling us where to go and what to do you actually have to listen or read the text to find out where and go and do it yourself. It was just add a little more purpose to the ghost collectibles and a little more to the world of Destiny. And if you were a guardian who was leaving a message for guardians in the future, what would you message say?