They have to keep making new focus trees. That's what interests most players and provides money for them to continuing supporting the games. Without them, we wouldn't be getting any bug fixes or general enhancements.
Seems like the least bad approach. Obviously it isn't working how must of us would like given that there appears to be a large and growing tech debt. We still have all kinds of things that don't work at all or work very poorly like peace conferences, battle plans, planning bonus, all kinds of naval shenanigans like aircraft only running two missions a day in certain parts of the world instead of three, and more. Most of these things haven't been touched in years, if ever.
As much as I enjoy HoI 4 it's clear that one of the fundamental issues is that the game launched in a much less sound state than more recent releases like Stellaris and CK 3. I can't see the game ever developing in a way that will fully satisfy people who take issue with some of the game's.. less sound mechanics, balance issues, and AI. There has been improvement in some of these fronts, but not as much as many people would like and I can't see that even potentially being solved until a proper sequel.
For more casual players, especially many of the ones that really fixate on focus trees, these nagging issues won't really matter. For more serious players that have mastered the game or play competitive multiplayer, they're serious issues and I know more than a few people who have more or less given up the game due to frustrations with these issues. I'm still able to enjoy the game in spite of its issues, although I've more or less been taking a break from the game the past few months.
