So let me preface this by providing some background on my gaming experience. I have not played HoI3. And while I've watched a let's play or two, that just isn't the same as actually playing the game. I have played various editions of Risk and some variants (Castle Risk and LotR Risk), various editions of Axis and Allies (including the 1998 computer game) and variants (primarily Pacific and Europe), games in the Civ series (and the spin-off/successor Call to Power II), games in the TW series (primarily Shogun 2), games in the HoMM series, EU4, and CK2 as well as games such as Wargame: Red Dragon, Sid Meier's Gettysburg, and games in the Close Combat series (especially CCIII: The Russian Front). I've also recently discovered the OCS games and am hoping to get OCS Korea: The Forgotten War for Christmas (in the meantime I'm getting used to the game using VASSAL). And I'm currently planning on getting HoI4.
So I understand that I can't speak to what functionality the counters in HoI3 have versus the functionality all of us can guess at in the models and counters present in HoI4 (let's face it, most of us haven't played the game and since the watching experience is different from the playing experience we won't really know the functionality of HoI4's system until we've been able to play it). But I can draw from my experience to guess at why Paradox made the decision to make the change they did.
From a marketing standpoint moving toward a system with giant models and counters that use less specialized symbols combined with widespread display choices ("health" bars and arabic numerals) makes a lot of sense. Many strategy games employ giant models. The tactics sub-genre often uses models, but they tend to be to-scale (or close to it). The wargame sub-genre often uses counters (generally NATO ones), though not always (some use blocks, such as the Holdfast series), and then there are the miniature wargames, which use models. Older editions of Risk used wooden blocks, but they seem to have switched to giant plastic soldiers. For board/tabletop games the strategy games with giant models are, in general, easier to find than the counter wargames. I have been in 7 Friendly Local Game Stores (FLGSs) around where I live and it is much easier to find the newest edition or variant of a game like Risk or Axis and Allies than counter wargames. If I drive or take the train about 4.5 hours south I can get to a FLGS with a decent selection of counter wargames, but that isn't really local to me. And with computer games the strategy games with giant models tend to be more well known than the wargames with counters. In other words, there appears to be a greater number of people who are familiar with giant models representing troops than people familiar with counters representing troops.
Getting as many people to buy your game as possible is generally a goal of most game studios. And so it seems that Paradox determined that moving to a system with giant models and less-specialized counters would help them achieve that goal. Granted, by not providing options to have the classic counter-style wargaming look it is likely that Paradox has alienated a portion of their player base and caused lost sales. Hopefully a future patch/expansion/other DLC will address this. Because these players are an important part of the HoI community. But I feel that the HoI4 system will open up the game to a lot more people, which is a good thing, because it means more money for Paradox, which means a larger development budget for the game's expansions.
Furthermore, as someone who is acclimating to NATO counters due to OCS Korea, I can say that they are not any more intuitive than giant models. After I have spent more time with NATO counters they will come to feel more intuitive. Right now one of my thoughts upon seeing the infantry symbol isn't that it represents crossed rifles and, therefore, infantry but that it looks like the start of a maths problem where I have to prove that two angles are equal to each other. That or St. Andrew's Cross. I know that the roman numerals at the top represent the size of the unit, though I still haven't gotten that completely memorized. A system that represented infantry with a sheep, reconnaissance with a fox, tanks with a rhino, and so forth would be rather odd, but if it were consistently used within a game and proper documentation were provided, such a system could work and might feel intuitive after a while (especially if the documentation provided the creative reasoning for the choices). Because at the end of the day, NATO counters, HoI4's giant models with counters, and the animal system are all representational. They provide an identifiable object for what is essentially a spreadsheet. Perhaps I should clamor for spreadsheet counters--let me have full transparency on the data modifications that occur as my units move about and take damage!
Interestingly enough the official documentation for NATO symbols is 376 to 400 pages long, granted some of that length might be from looking at the commented version, but there is at least 100 pages of symbols. Just look up the APP-6A. It's unclassified with unlimited distribution, so no worries there! Also, the "boxes" for the symbols varies with whether the unit is friendly, neutral, hostile, or unknown and there are truncations of the shapes to represent space/air and subsurface.
