People loved it with CK2 because it expands the game so much, and it was unlike what they were doing before. This helped people forgive the fact that the base game was just okay at launch. Contrast that to HoI4 where the base game was not fantastic at launch (but probably not much worse than CK2 at launch in terms of stability and systems) and then the DLC train started and I saw a lot more negative comments online. There were similar conversations around the Stellaris launch "Oh they are going to make us pay or features that should have been in the game in post launch DLC".

That could just mirror changes in players being hyper-sensitive to DLC/Monetization strategies these days, and probably don't bother the people who are really into Paradox games and put hundreds if not thousands of hours into them.

I am very interested to see what they do next with Crusader Kings, since they have mentioned a few times they plan on ending the DLC soon. Transitioning to a CK3 seems incredibly difficult given how barebones it will feel.