Actually, the more prevalent use of Greed is to lot on items for jobs you're not on currently. For example, I'm going through a dungeon on SCH, but a robe drops that would be great on my SMN. As it's not suited for SCH (Note: The ability to Need is based on if it suits your role, not just if you can wear it), I cannot Need on it. But I can still Greed on it.