Well, I'm not a game developer but still a software engineer

As a software developer, it is totally natural, that I want as much memory as possible, just so I don't need to worry about it. Yes it saves some time, but it is most time the most inefficient way and optimization not only helps to reduce the memory footprint, most times it also helps to reduce other resource-cylces you could better use for other stuff.
Also a big difference is, in the current gen GPU resources had to be inside of the memory just because you couldn't stream them fast enough. This is no longer needed. From the SSD you can buffer only as much as possible from the resources that no longer must get packed into packets so only things that are needed are loaded. Additional things like SFS are there to further reduce the memory footprint of needed GPU resources.
The only thing that can get a problem is gameplay logic. But to be fair, we haven't seen any big increase in memory footprint for gameplay logic in the current gen. All games are more or less still the same as on the last gen but with better graphics. Even open-worlds games are more or less still the same. HDD streaming in the last gen made it possible that the worlds could get a bit bigger (not optimal, but way better and faster than disc-based streaming).
But still, gameplay wise, it were more or less the same games. Scripted AI and scripted events. This is still used, because for a developer it is just better to predict what happens than using AI (wich is much more complex and resource intensive and much less reliable).
And because of the asset thing. Assets have always different qualities, because you need different quality steps if things are far away from the camera. Not really because of optimisation (that is also a thing, but it is not the only reason) but because it wouldn't look that great if you have something like a character that is far away and the polygons and details get smaller than pixels. This could lead to graphical glitches which you don't want to see. Therefore you always create models for different stages. Just don't load the higher sets and the memory footprint is automatically lower. This is no extra work, it is work that must be done this either way.
btw, AC Unity had a CPU resource issue. Btw, the engine worked fine with later AC titles, so they seem to have fixed that issue.
The 0.2 Ghz less cpu frequency won't change anything at all. Well I don't really get why they downclocked it, but well, after all, CPUs in games are more or less only doing GPU preparation stuff, so less GPU-stuff -> a bit less CPU stuff.
Won't change the fact that PS5 CPU & GPU configuration is much less predictable.