I felt this way for a long time, but I realized that much of my frustration was coming from a mismatch of my expectations and how the game expected me to play. When I stopped caring about losing progress or dying, I began to appreciate these games for more than their challenge. Ultimately, these games are RPG sandboxes, and the fun comes from trying new weapons, magic, and builds as well as the sense of wonder and discovery that Miyazaki's games create.
There are difficult elements to this game, but it's entirely possible to simply sit back, relax, and not feel stressed when playing. Losing souls is meaningless, and grinding is only helpful if you're incredibly underleveled. Dying is an opportunity to learn, and if you're still losing then that's a good thing- there's more to explore and understand. When a game fails to offer new challenges or things to learn I am no longer having fun. Relaxing, to me, is spending time staring at a map to plan a faster route or exploring a boss's moveset to see if it has any glaring weaknesses.
I can appreciate that not everyone enjoys experimenting like I do, and some people want gameplay to service the cutscenes over creating unique gameplay opportunities.
Edit: I also wanted to mention that, though I have a very intense job, I still find these games fun. It's nice to have a sandbox to play in that has encounters to break that work on my time. I feel in control when I play a souls game. I know that there's a path to victory and a strategy I've yet to try. This isn't a situation I find myself in in real life very often.