What I'm finding most fascinating about all of this is that, before the new consoles specs were revealed, just about everybody was putting the blame on the old Jaguar CPUs for the 8th gen's bottleneck, and for the life of me I don't remember anyone even mentioning storage as the culprit. Now all of a sudden the SSD is the only thing that matters.
And yes, I understand that higher SSD speeds will allow to stream more data faster, but that data needs to be processed in the first place. You can have all the storage speed and memory bandwith in the world, but if the CPU and GPU cannot keep up, you're just going to end up with a waste of bandwith.
Everything is relative though, and I guess ultimately the approach both Sony and MS have gone with is fully dependent on the cost of components and the diminishing returns of linearly progressive hardware spec bumps. 5 years ago I don't think many of us thought that things would have slowed down as much as they have comparative to price. Price being the major factor here that has skyrocketed.
That is to say that usually we see huge amounts of RAM upgrades every 5 years. So much so that on average we generally see a RAM increase by a factor of approximately x10. PS1 -> PS2 -> PS3 -> PS4. Going from PS4 to PS5 is only going to be twice as much RAM. Why? Cost of RAM is ridiculous. This presented Sony/MS with a dilemna, how do they achieve a generational leap while still keeping the cost down? Here is where blazing fast asset streaming comes in. Cerny touched on this heavily in his presentation - whereby your SSD (800+gb) can almost act as RAM (not quite but almost).
Ultimately this leads to maximum utilization of your 16GB of RAM. You will see that a general theme of the next generation consoles is maximum efficiency in using what they have.
With regards to CPU power - there wasnt really much thought needed on this one. 8 zen2 cores was always going to be the standard given what we see on desktop along with price. Again bumping this to 16 just isn't feasible from a cost perspective and anything less would be hopelessly underpowered with no way to make up the difference. Perhaps if they did decide to spend the resources on more CPU power it might have come at the cost of their SSD and IO solution along with a better heat solution and bigger form factor etc. So again the logical decision was made, and this is a decision made by both manufacturers leading to little or no needed discussion on the CPU front.
Personally, with regards to the GPU i see it as a exactly the same way as I do with the CPU. Latests RDNA 2 architecture with decent clock speeds, is really all that is required. Anything less again would have been waaay to far behind, and anything more is probably too expensive, too big and too hot. This seems to be the only area of deviation though between the two manufacturers, MS goes with a bigger GPU die, while Sony pushed some hardware processing to assist with IO through put.
And thats why we find ourselves here with all this SSD talk.
If things had progressed as they have been 10-15 years ago we would probably be talking about huge amounts of RAM like 64gb and 16 core cpus clocked at 10ghz etc..
This also leads to Cerny's comment about equating PS4 teraflops to PS5 teraflops. Devs and Engineers are finding new ways to overcome limitations and the hardware manufacturers are following suite and building to cater to those needs. If they know to focus on certain areas then processing of a particular type of load becomes more efficient - but it doesnt necessarily change the teraflop count. Its the same concept as running Ray Tracing work loads on a monster gpu from 5 years ago - its pointless.