[microtonal]

It's an interesting point, but seek times and rotational delays don't apply to SSDs.

There is another reason to do compression on SSDs: you have more storage free and thus less write amplification and your SSDs will last longer. In fact some SSD controllers (e.g. SandForce controllers used to do this) compress data to reduce write amplification.

https://en.wikipedia.org/wiki/SandForce#Technology

The trick that they applied is that say, if you had a 500GB SSD and you stored 400GB uncompressed which the controller compressed to 200GB, the drive would still report only having 100GB free, giving it an ample 300GB of free blocks, thus greatly reducing write amplification.

(Of course, the benefit of controller-level compression is gone with full-disk encryption. But I guess FDE was less popular when SandForce SSDs became popular.)