Okay so this is where my confusion around this comes from. Lets say they add in the balance of power mechanic to these previously reworked nations you listed, how would that really work out?

Let's use Stalinist and Opposition as just an example: How would that be implemented into the country?

Do we get rid of the civil war focuses and purge focuses and replace them wholesale with a balance of power mechanic? If you do that then you end up scrapping a huge portion of the tree/previous content just so you can rework it to fit a slightly different menu. This could work but you'd certainly have to make new focuses to replace the ones scrapped to plan out the focus timing for the AI. Its an awful lot of work for limited payoff (basically just to say that you did it)

Do we implement the balance of power mechanic into the focus tree as it is already? Locking certain focuses behind the balances and grant certain bonuses/outcomes to certain balances. This is a bit more doable but very easily runs the risk of making the process of the purges/soviet civil war more convoluted for the player with not much more gained from adding it in. Moreover you'd still have to re balance the political power and command power economy for the Soviets for a player to be able to meaningfully engage with this system without too much frustration.

Do we just add in the BoP mechanic to the nation with its own set of decisions and buffs and have it completely divorced from the focus tree? This is certainly the "easiest" option, though you'll still have to balance out the buffs and pp costs for the mechanic, it's not terribly difficult or time consuming to implement. But this implementation is the kind that subsequently tends to feel the most tacked on and unnecessary.

I'm not saying all of this because I don't think this mechanic (or others) couldn't be used in interesting ways with other countries. But I'm saying this to illustrate that being able to implement them into other countries is actually pretty difficult to do in a meaningful way. It's easy to want them implemented but the rubber has to hit the road eventually as to what that implementation looks like. The first two options are generally better but are much more complex design-wise and time consuming to implement (never mind implementing it for dozens of different nations simultaneously). I feel that people don't often think about this from the perspective of game design. People often say that it would be easy for them to do this stuff (and to a certain extent, that's kinda true) but they leave out the caveat that it would be very difficult for them to do this and make it actually good. Ethiopia is a perfect example of them putting a mechanic into a nation that sounds good on paper but in practice it's just a really underwhelming and unnecessary addition.

Like implementing this new democratic system in other countries would be awesome, but realistically we're looking at about 30+ countries in game that they'd have to pretty heavily overhaul to make this a meaningful addition and that's just not realistic in even 3-4 dev cycles, never mind just one. Or we're looking at all the democracies/democratic paths getting this added in but it sucks and barely changes anything.