Older readers probably still remember: there was a time when telephones didn't have buttons but a rotary-dial for entering phone-numbers. It was a very robust usability-concept: usage was intuitive, could be understood instantly and was quite error-proof. Anyway it is common-sense these days that rotating elements in computer-interfaces are bullshit and in most cases I heart-fully agree. The more astonishing it is to see rotating gui-elements popping up in every corner suddenly. After all in the physical world rotating movements do accommodate human motor activity quite well, but unfortunately this concept cannot be translated 1:1 into the world of computer-applications with all the mouse-controlled clicking and dragging. Apple had to find this out in the early 2000s when they integrated a thumb-wheel into Quicktime-player 4. It was one of their less clever ideas and Very soon a slider was used for volume-control in quicktime-player again.
Mainly audio-software tries to mimic the experience of real-world audio-tools like amplifiers, mixers and effect-appliances on screen. Screen real-estate is limited, but audio-software often needs to put a great number of control-elements at the same time into user focus. In this case it can be beneficial to use dial-controls which take up less space on screen.
But the big times for the rotary-control still lie ahead: the new generation of input-devices with multi-touch controlled interfaces in touchscreen-displays did create a new interest among designers for the dial-control. It has a big benefit against linear sliders: it doesn't need a beginning or an end. I can loop endlessly through my music library, rotate objects or change color-palettes. Apple once again were the pioneers by successfully integrating a control-dial into the iPod 2nd generation. And the best is yet to come: