pretty vs useful

in regards to ui on touch screens (or any ui, really)

real dials are meant to be grasped with fingers
you cant grasp virtual dial and left with having to rotate it with circular motion. finger has no guide, no natural direction.

real sliders could also be grasped, but most of the time they're pushed with a finger. that vertical movement translates perfectly to slide/swipe movement for a virtual slider.

dials are nice to look at. they remind us of hi-end amps and expensive car interiors. but they have no place on a touch-based device.