Paradox releases broken, unfinished games and you need to wait for multiple paid DLCs for the game to end up in state it should start with.
I don't have a strong opinion, some games definitely had bad releases.
But... I am not the expert 500h player. Each offers enough mechanics/content/missions to be entertained for a while. Even without any DLC. Put a new players on even the base HOI4 (which is already a streamlined HOI3), and see him drown in complexity and possibilities.
And this is their business model. Don't try to build the SP/Coop/Casual Multiplayer/Esport-level MP all in one. It would fail, instead: build these for-the-fans games, and then expand the popular ones with 5 years of monetized DLC. If you don't like the medieval 4X, go with WW2, Space or discovery age.
If the launch content is limited, if the technical quality is mixed: It is part of their business decision. They used to price games like €40, helps a lot with the value perception.
In conclusion: Paradox games (regardless of quality) launch with the audience and the business plan in mind. Limited features, limited scope, limited audience, limited expectations - it is a functional business model.
Which is unlike CoH3: launching to appeal to everybody, and the chaotic monetization plan.
https://store.steampowered.com/app/1317230/Hearts_of_Iron_IV_Allied_Armor_Pack/
https://store.steampowered.com/app/1579991/Hearts_of_Iron_IV_Eastern_Front_Planes_Pack/
Monetizes. And it also does it worse than modders who make models of better quality. The Paradox as a whole is very bad. Their DLC is constantly underdeveloped, poorly developed. But since this is a niche product and there are few or no similar games, Paradox can simply exploit the fans of their games.
Well, I guess there are some vanity items for sale. Some throwaway historical model expansion. And I suppose TW games have the "Blood" cosmetics.
Regardless, you can see the amount of reviews - game racks up 50k players on Steam at the peak time, yet the DLC has 205 reviews. It is junk, you cannot build the business model on selling skins/vanity packs in that game. It is all about selling copies/gameplay DLC/Expansion-sub.