a lot of audio stuff is designed with the expectation that you'll be binding the control to a MIDI controller if it's important, so in that sense the skeumorphism makes a lot of sense. if the VST knob is just a visual representation of something that's bound to another MIDI-bound knob in a DAW, it doesn't really matter if the mouse UX is bad, since it'll probably only be used briefly while dialing in settings, and then serve as a visual UX thing after