I would like to see an rpg implement this properly. Imagine that you are visiting a city, a small town or fortification and it's being attacked by giants, the next day people are working on to restore the damage and in the following days the city returns to normal. There maybe hollydays when stores offer special escort quests or a plague of vampyres that needs to be cleaned. This game mechanics offers quests which are endless resources of experience for whatever role-palying style the player is developing and it's also fun to explore the game world this way looking for special events and unique questing oportunities.