I do it because I think most things are very over priced. I normally keep all my crafters and gathers maxed and I see very little reason for gil (for me at least) if I want/need something I can craft it or gather it. If it is a dungeon drop I will just grab some fc members and go farm for a bit. Already have a house as well so really I have no need for gil so I don't mind if I sell something really cheap, as long as someone can use it.