We didn't have rainmeter back when hard drives were used as boot drives. I have a pretty large set of windows performance monitor and HWInfo readouts running on all of my windows machines with modified versions of the simpleperfmeter and now rainformer skins.
No need to have uncontrolled diagnostic feedback when you can make it be exactly what you want in a much more rich/dense format. Clicking doesn't tell you much compared to time traces of read and write activity, drive temperature, and page fault rate.