I actually think HoI3's HQ system is one of the worst systems Paradox has ever invented. You have multiple different HQ units, all of which have different radio ranges and need to be in range of different units. And then whenever the front moves forwards or back you have to move all of them alongside it. Its a mess, and there's very little to justify it as there's no good way to gank enemy HQ units aside from them messing up. The only thing to recommend it was the multiple leader levels for each troop, but even then it had the effect of diluting the effects of a commander and making all armies feel about the same in terms of command effectiveness. You might have one unusually good commander in EU but in HoI 3 you're hardly going to get any noticeable difference when there are 5 levels of command. And its not like anyone was going to each province like "this specific group of 3000 infantry needs +20% chance of elastic defense tactic."
This is probably too technical for a discussion here, but what's important to realize about HoI3 OoB is that the leader skill bonuses from most HQ levels aren't important (division and army group skill levels are the only relevant ones really, and sometimes theatre), and that trait dilution is at a relative level. So an "Army Group" that in reality only has 5 divisions directly attached to it will have the army group leader give 50% of their traits bonus to those divisions, as though they were a corps leader, and 25% from the theatre commander. This means that you can make a lean and flexible OoB where radio range and the need to constantly move many HQs forward is much less important, while having more concentrated trait sharing in places where it's relevant. You can have an army group with 4 divisions and an army, have a smaller force of <25 divisions that skips corps and armies altogether, or use any combination of configurations to get the quantity of divisions, radio range, or traits you want, and for me I find that extremely enjoyable to work out and see in action.
Even if you stick to a more rigid OoB as a major, there are benefits to having some small groups get a trait for river crossing, offensive/defensive, terrain specialty, etc, and it's only homogeneous if you choose to structure it that way.
I somewhat agree with the "press a button not to trip" analogy, but only because it's the AI that can't handle a complicated OoB, making a well-made OoB a player-only advantage. In HoI4 this AI disadvantage is improved, but only because the system has been made as brainless as possible. I would rather just give the AI +15% combat efficiency or something than cut out what I would consider one of HoI3's defining mechanics; maybe OoB could've been trimmed down a bit or made more focused on specialization rather than general bonus stacking, but eliminating it completely is almost a dealbreaker on its own for me (it's along the other changes that also make HoI4 feel like EU4 in WWII that bother me enough that I'll be steering clear of it).