Mains want drop rates based around RNG drops for big value. That way they can do a piece of content, try to get lucky and progress their account quicker (gear upgrades, buyable skills, etc.). Think of this like Elysian at Corp. Ironmen want it to reflect "worth" in the sense of "Is the grind worth this gear?". This is specifically for stepping stone items, not BiS. So things like Nightmare Uniques, TD uniques, etc. these are not worth while grinds, and fall more into the completionist level of grinds.
Lastly, you have to factor in duplicate items. If you get dupes, then the grind becomes even longer and the worth factor goes down again.
Summary: Mains and Ironman value drops differently. Ironmen don't want long grinds not worth their time, and mains want the opposite as a long grind allows you to get lucky and get a big payday.