During this time, synths with knobs were revered by players, but not provided by manufacturers. It was baffling disconnect between what musicians (said they) wanted and what the industry made.
I don't think it's that easy to characterize, from a UX perspective, given the rapid changes in technology taking place under the hood.
If you compare the one-knob-per-function Prophet-5 to the Prophet VS, or the (one knob per two functions) OB-8 to the Matrix-12, you already see the challenges in reconciling the underlying technological capabilities with a one-knob-per-function binding:
- VS: button-as-parameter-selector plus data-entry slider, as used on the Yamaha DX7
- OB-8: shift-functionality using Page 2 functions, silkscreened on the front panel
- Matrix-12 / Xpander: Page N functions with multiple contextual knob + text-display parameter values*
And it's safe to say that nearly every modern instrument which lacks a touchscreen uses some combination of these concepts in differing amounts.
In most cases, it took quite some time before a (handful of?) generally-accepted approach(es) to parameter access was an agreed-upon if understood context for instrument designers.
* - the Waldorf MicroWave falls into this category, albeit with a displaced positioning of the display relative to the knobs.