Putting/letting Jony Ive on designing the new campus is one of the dumbest things Apple has done. Effectively dereliction of duty.
Now that he's back on task, I'm holding my breath that there are some mea culpas in the next round of hardware updates. If there aren't some significant quality improvements I'll probably still get a new laptop, but I'll be selling my shares.
That explains it. I hadn't actually used one before purchasing it but had used the previous generation model a few times.
The size need only be proportional to the amount of hot data. And realistically, it need only be proportional to the amount of hot data that's randomly accessed in small chunks, because that's where the bulk of the improvements will come from.
I wonder why the performance ain't so great. I bet 32GBytes is in principle more than sufficient.
[1] https://en.wikipedia.org/wiki/Fusion_Drive