Then why not just the 9? I mean it's not like the middle 8 couldn't be shoved into the other 9 as layers. And generally far better layers than the ones the main 9 accually have. Because even in the main 9 you get your fair share of filler places. Infact even in Hell and the Abyss only a small % is accually made interesting everything else is just generic infinite made for no other reason than "THE OUTERS ARE INFINITE PLACES OF INFINTE"(TM).Seriously though: They are the "Paraelemental" Outer Planes. Hell, Hades and the Abyss are effectively thriving communities with their own outlooks on things. The in-betweens appear to mostly just be blurry conceptual hick towns where things are given some breathing room to be a little less black and white, and I'm totally okay with that given that each of the Cardinals is an entire universe in and of itself.
Infact why not just throw the wheel out all together and make the planes nothing more than dungeons to fight stuff on...oh wait 4th did that. Well i can certainly see why they chucked the wheel. If you aren't going to do anything with 90% of it why bother redoing it for your books each edition?
And that would be fine if the Blood war was "fighting because even if they were all exactly the same alignment or even the same guy copied infinitly they'd still kill each other for fun and games". But it was given this huge law vs chaos aspect to the point of the box sets being the planes of law and the planes of chaos. When in practice it was never presented as such except on the tin.The Blood War is only so constant because the lower planes get all the psychotic pricks and the Yugoloths in the way of the fight are acting to gleefully facilitate it whilst playing both sides. Frankly the Modrons and Slaadi are probably too repulsed by one another's home ground to bother wasting time with a large number of concerted organized raids when they've got better things to do
Just poor design when you hype up a war of the outlooks and then just make it between beings that would fight over anything anyway.