I really don't see how HoI was about "so much more than that". HoI and HoI 2 were wargames, just like HoI 3 was. Their primary focus was on the war, anything else was a sideshow that hardly mattered at all.
I'm sorry if I sounding too exited, but I can't really understand that. Hearts of Iron series are games about 1936-1949. Hmm, let me think - what are the main event of this period of time? I don't know, maybe it's World War 2 - the biggest war in human history. The war when tens of millions of people fighting each other, and those armies wasn't organized in thousands of divisions only. There was very huge, deep and complicated military structure and HoI3's OOB is only place where I can dive into that staff, research various things about it and change it as much as I want or how it was.
Ok, I obviously did not make myself clear enough, sorry for that. The war is, always has been and always will be the central element of the game. However, there are different ways to approach the implementation of the war into a computer game. One would be to solely focus on the tactical aspects of warfare. Let's call this branch "General/Heeresleitung Simulator". This is what Panzer Corps and games like that focus on. There is another approach though, something that made HoI unique: the focus on how to steer any country through the troubled times of the second World War. Of course, nationbuilding is reserved for the likes of Vicky and EU4 (and they do a great job with that), but HoI, in my opinion, has always been more than a mere warfare simulator. It is more a "Countryleader/Führer Simulator".
HoI2 was deeper into that specific country aspect than HoI3. First, there were nation specific tech teams. Then we also had those sliders that would determine certain parameters of our nation (autocratic vs democratic, planned economy vs free market, politcal left vs political right, interventionism vs isolationism and so on). Even the espionage system was way better in HoI2, I remember stealing blueprints from major powers and that really could make a difference if you had bad tech teams at your disposal. In HoI2, especially with the sliders, the players could kind of "create" their own country, each way the gameplay would be greatly affected. The most important point though is, that the player had more to do during peace. Stealing blueprints, trying to sabotage the enemys production, adjusting sliders to change your country and so on. The warfare aspect was (way too) minor. With HoI3 they went into a totally different direction, all of a sudden it was all about warfare and the rest was rather redundant or you just didn't have much time because micromanaging your troops sucked your time budget up.
With HoI4 they are trying to merge both concepts. This will naturally take some of the focus away from the warfare aspect, leaving all the OOBs and divisional commanders and stuff in there and then adding the pieces that made HoI2 great and successful would overburden the game. So what I actually want to ask for from anyone desperately trying to pursue PDS to "keep" all the tactical warfare stuff in the game is to understand all those players like myself, who liked HoI2, even though it didn't bother with much tactical warfare. I liked HoI3 for the tactical warfare, but there was something special about HoI2, otherwise it wouldn't have been played by so many for so many hours.