Just a point to showcase how important that actually is.

My BF is currently going through the campaign and he's fairly casual. When he reached the end of HW and had to do the last story dungeon with the NPC (with bad gear leveling gear as he ddin't upgrade stuff once hitting 60), the last boss (Ascien fusion) killed him quite many times. After many attemps, he managed and was proud of himself.

Then he had to queue for thordan which was killed in a few seconds.

I recently showed him my reclear of DSR.
When he saw the phase 0, he was like "oh yeah that was a cool part, the boss was tough"
When he saw thordan "did I do this guy?"

He does not remember thordan.

He doesn't even recognise thordan, he knows the old man, but not "Thordan the boss" because the boss died in 25seconds.

Casual/story content being too easy also ruins their experience. How can something be memorable if a random leveling mobs poses more of a threat.