Interesting about your putting GOW '18 over GOW:R in gameplay. What did you like more about '18? It's been a while since I played 2018, but I thought GOW:R refined and expanded on it from what I remember.
It's a combination of factors.
Played them back to back at GMGOW difficulty and found GoW (2018) much better tuned, every encounter felt perfect whereas in Ragnarök I noticed in many instances limitations in the camera system, to say one.
Axe and Blades also felt (and sounded) much more impactful in the first one.
Also hated the linear sections in Ragnarök, mostly because story and characters felt dumbed down quite a lot to me.
Plus, no procedurally generated farming levels in Ragnarök, and since I did all side content along with the main Quest it meant basically no end-game content as I saw no reason to put hundreds of hours in the game like I did in Ivaldi's maze.
Boss battles in Ragnarök are amazing and the Crater level design is absolute perfection, but I just prefer the first one because it felt like a real arcade game instead of whatever Ragnarök wanted to be.