I just ran with a map party with friends and this question only occurred to me when one of them Needed on something before the rules were mentioned. Of course it was brushed off but I'm curious as to what this does for the given party.

I understand in dungeons and trials and raids Need is available only for gear that your current job or class can use. But then we get the oddball items: crafting items, mount whistles, minions, etc. Isn't the Need option available on all of these for everyone? DF rules are coded in the game, my question isn't about someone setting the DF rule to Greed only. My question goes more for duties like Aquapolis where the rule has to be established by the party. Here, all "Greed only" does is make it easy to spot someone that's breached this rule, despite, again, Need being available to everyone.

That being said... it's really late at night here and I may not be considering the cases where Need is not available to certain people on certain items in Aquapolis or treasure maps. Also, I'd like to stress that I'm just trying to ask about the logic behind such rules. Personally, I pass on 99% of the items that drop, and for items that I might want I ask about what I should roll.