Is there any actual evidence that "nobody wants to twist generic looking knobs"? It seems like a widespread assumption, but I don't know to what extent it's been measured or tested.

I, for example, am a nobody (a hobbyist musician) who dislikes most custom VST UIs. Back in the day, FL Studio (nee Fruityloops) shipped with a bunch of plugins that looked like they had an autogenerated UI, with every parameter getting its own controls (a knob, numeric readout, and visual bar)... and I liked them. No cruft, and it was easy to systematically manipulate each control to determine its effect on the sound.