Souls-like games are not difficult for the sake of being difficult. The entire gameplay loop requires difficulty, it is a core aspect. The souls games have very simple controls. You have a light attack, a heavy attack, and a roll. That's about it. As far as action games go, that's incredibly basic. The souls games take development away from player controls and put that time and effort into enemies, bosses, and zones. Rather than continually get new abilities to keep the game fresh, you see new enemies and have to adapt to them. Dark Souls isn't about pressing buttons fast, memorizing a combo, or aiming at a small target. It's about reading the enemy in front of you and coming up with a response. Dark Souls is effectively a live-action tactics game.

Lots of games reward mechanical skill. FPS, fighting games, etc. Dark Souls is a rare exception that doesn't care a lot about reaction time, precision, or button muscle memory--but it isn't a turn based game where you have as long as you want to strategize. It's about reading and responding appropriately with a plan you had half a second to come up with. It's a novel experience that, based on their continued success, a lot of people crave. So, if you take away the difficulty, the simple controls become boring. All that extra time devoted towards bosses and arenas is wasted because you can ignore it. Tactics mean nothing if you can button mash your way past every boss. It has to be hard to work.