Because such a mode would only be truly accessible without death and the risk mechanics of Dark Souls. In such a super easy mode there would be no worry over bonfires respawning enemies when you rest to recover because you'd never need to actually rest to recover in such a mode as any peril or death would make it inaccessible.Yes, that particular mode was way too easy. As in "if you were having problems with normal mode, this particular easy mode goes way too far, making the gap between the two too wide, in my opinion."
You also didn't answer the "if the easy mode is still a challenge, then how does it hurt the "Dark Souls should be challenging as part of the game"" question.
Easy mode that is accessible to all will by necessity have to be a giant difference between it and Normal mode. That is why Easy mode is NOT the solution.
Almost all media has some level of skill requirements you just likely didn't realise you were learning the skills. With films you have to recognise and understand certain film tropes and conventions which allow some level of short cutting the story. When film were first invented and being shown they had to teach people to understand the train on screen wasn't about to come out and run them over for example. Some people still struggle to use their TV remotes but to engage with TV that is a basic requirement.
There's no harm in the easy mode other than the obvious fact to have an easy mode that is truly fully inclusive it would have to be a 1 button click auto playing game almost. You know an idle clicker or the like. Part of what makes Europa Universalis have appeal to people is the sheer depth to the game, learning all the systems and how to actually work them. The reason people play such a game is for the depth and challenge of it.Because I've played a fair bit of Monster Hunter. Dark Souls is, thus, not particularly challenging outside of specific systems knowledge. Am I playing Dark Souls wrong because I don't think it's any more challenging than Monster Hunter?
What's the harm in Europa Universalis having an optional easy mode?
So my question again is why must people play Dark Souls? Could they not play any other number of medieval fantasy games?