> More and more both personal computers and servers are using ARM CPUs without AES acceleration, though.

The RPi SoC is an exception here - most ARMv8 SoCs should have AES instructions.

> Also, write speeds of modern SSDs comes to be over 5 GBps.

True, but I don't think the expectation is to utilize that throughput with a single application, rather, to still have fast I/O even under load or with multiple applications, and to satisfy burst I/O quickly.