One counter to this argument is that, while the CPU has thousands of cycles to do compression while an old 5400 RPM spinning rust drive seeks or writes, a modern SSD like the new Samsung 960 Pro can write data at 2100 MB/s, giving the CPU perhaps one cycle per byte, which makes compression difficult.

The counter to my counter, of course, is that specialized silicon for compression can easily keep up with even these speeds. In fact, Sandforce SSD controllers build in compression to boost read and write speeds!