Why did OKW go through such a radical redesign in the first place?
Because their original design was, whilst a cool idea, absolutely trash when implemented into CoH2.
A faction designed with enormously powerful units and defenses that only has to hold 1/8th of the map for half an hour to win was boring and stale in 1v1, and utterly ludicrously broken in 4v4. Frankly, the latter problem still exists, largely in part thanks to the lingering faction design elements still present since the beta.
A lot of the reason it was boring was that it was the utter height of the (oddly ahistorical) 'axis win if timer goes past X' philosophy that we've been fighting with Relic to avoid since the beta of CoH2's eastern front. Either you bashed your head against a wall until it fell on you or you wiped them in the first 10 minutes. It's the FHQ gambit's frustrations only represented on an entire
faction in multiplayer.
A lot of design choices that seem good for the original concept have just stuck around with no regard for how they function outside of that. And a lot of them are sorely in need of fixing.
Reinforced wire form T0 initial units, for example. When your entire livelihood requires you holding a small chain or territory with a truck in each, preventing ugly flanks is a necessity. Reinforced wire = able to lock down better, good job.
When you're now playing as a normal faction with a faux 'fuel starvation' and units out of the wazoo, it's dumb as all hell, but it remains.
The Schwerer HQ is pretty much the pinnacle of this. Every other faction has to spend to tech and that's that, if you're USF you get a squad rather than a base building. The OKW, as a faction requiring holding a chain of ground to a fuel point, needed a deterrent, an AA option, and a way to hold down their ground.
Now they're just a normal faction with a faux 'fuel limitation', they get to tech and, for free, cut off an enormous swathe of map via choke points to the enemy from their first 80 fuel generated, demanding a huge investment of time and resources to kill even when unsupported unless you have tanks
at least as heavy as a T34. And it's dumb as hell.
Allowing your core, front line infantry the best handheld AT weapon in the game and fantastic vet made sense when they were never going to be getting tanks and needed to be able to hold them off their trucks. Now... you get the idea.
OKW suffer from being a faction designed to work a completely different way shoehorned at last minute into a different role without anybody thinking that, maybe, you should take away all the super special toys they were allowed to keep themselves alive with only a tiny area of the map now they can contest it all.