Agreeing with the rest but not the end.
> We're still seeing Moore's law for drive space,
Not really. 2Tb became a standard a long time ago, and it didn't change afterwards. Speed did not improve much either, especially latency (it cannot really improve), except by switching to SSDs, but then you lose capacity, so it is not a continuous improvement.
> RAM, and somewhat bus speeds, and that's also where you get a lot more speedup.
SDRAM is slow as molasses, as far as latency is concerned (the "Random Access" in R.A.M.). The improvements have been incredibly small in this domain. DDR4 access times are slower than SRAM access time from perhaps 20 years ago. It has however much larger capacity and larger throughput, indeed.
> and somewhat bus speeds, and that's also where you get a lot more speedup.
Same problem with buses, their frequency raised a lot, but that happened with switching from parallel to serial buses, leading to a lot of latency (and overload), not only on the bus itself because of the protocol, but also before and after because you need to serialise and then deserialise the data for you need it in a parallel form anyway.
For example, the first SATA, despite its impressive frequency of 1.5 GHz, did not do better than the good old IDE/PATA with the latest UDMA.
Same for PCI Express, it showed 2.5 GHz frequency, but its performance was not better than AGP or top PCI with their < 100 Mhz frequencies.
Then to improve the throughput you had to add multiple lines of serial buses, which again add some need for synchronisation and thus extra latency.