I'm convinced that the reason CK3 hasn't hit like CK2 is because of the writing.
The game has systemicized so many things that were previously handled by cleverly written event blurbs, and in theory that provides more interactivity, and we love that from CK, but the lesser sung essential component to CK in my opinion is the game's own baked narrative beats that serve to keep you inspired.
CK2 is renowned for it's humour, yes because of the moral questionability of so many strategies you are the agent of, but heapingly also because the writers on the team were in on the joke of how absurd your alternate history would get, and deliberately scripted events that enable you to install your horse as chancellor, or have your daughter be the spawn of hell.
Obtuse game mechanics and a UI that took hundreds of hours to penetrate were forgivable and worth the investment, because the narrative fantasy being delivered was so irresistible. I think CK3 is right to have focused heavily on revamping and streamlining the mechanics and UI, I just think there isn't enough inspired narrative in the form of writing.
The disparity here between the two games can be attributed easily to the length of content development, given CK2's obscene number of expansions, but I think even for a base game CK3 was released super under-baked in the narrative department. I get the feeling it's release was rushed, and it makes sense that the narrative content would be the last part of the game to be developed after the systems were solid, so that's what suffered, both in quantity, and in quality. I can't imagine anyone on the dev team could be proud and consider it the right move to have events that set up something potentially narratively interesting, allude to varying potential outcomes to how you respond, and then, once you've made your choice, discreetly enact one of the potential mechanical outcomes while unpausing the game, coldly leaving you to infer what may have actually happened.
I think I can understand how a panel of mechanically-minded strategy game enthusiasts might overlook this, or not understand what they're missing, but as far as I'm concerned, all the systems in the game are merely tools to immerse us in the fantasy of being a medieval ruler, and provide us with a narrative experience that is both uniquely a product of how we play, and, even more essentially, rich. I don't think CK3 delivers that narrative richness we ultimately crave, because it hasn't been written into the game in the same way it was into CK2.
It's my hope that ongoing development can rectify this, but for the game to really come alive I think they should do a pass over all the existing writing in the game, and write outcomes to all the events etc.