I don't think people understand what exotics are in Destiny. You assume exotic means: super rare drop. Destiny defines exotics as: armor and weapons that contain unique perks that allow further character customization. The reason this is hard to grasp is because Bungie needs to create a new color for "raid gear" which is different from other legendaries. Do the tiers talk about drop rates? Yes, but not to the degree that you expected. People need to understand what Bungie means by exotic so this community can move on.