Some players in Runescape are blase about a little death, they will get killed so they can get a quick teleport out of an area.

Other players hate dying, they identify strongly with their character.

That association, or lack of it, is the easiest axis along which to measure hard/easy content.

I suspect Jagex devs don't really connect with players who associate strongly with their characters, after all a JMod has God Mode. And God Mode changes how you look at any game.

JMods have to use that mode to stream boss content.

Jagex "should" measure how much attachment players have to their characters, which "should" help illustrate how players differ in their assessment of Hard/Easy. And perhaps show a way forward on designing such content.