Why did color knobs disappear?
Because there wasn’t a consistent rule to explain the use of color, in particular with the generalization of attenuverters (no need to visually group a parameter and its modulation with a knob of the same color) and the increased complexity of the modules (many independent dimensions of sound control, as opposed to 2 or 3 in the early modules).
This is how the process of chosing knob colors went...
Braids: white for everything frequency-related, turquoise for the secondary parameter and its attenuverter, fuchsia for the third parameter. Yeah! And we get some rough 70-20-10. How pretty!
Edges: we can keep white for frequency, and turquoise for the secondary parameter (gain).
Ripples: yes, white for frequency again! The others can have another color. But now it’s 33-33-33
Grids: mmmm - ok we can find something here but obviously there won’t be any logic.
Tides: if we follow Braids’ precedent, the top two would have to be white since they are both related to frequency, but what to do with the other ones? all turquoise? all fuchsia? a mix? If we want some balance, FREQUENCY will have to become turquoise.
Yarns: oh, that one is easy!
Frames: we can’t use turquoise for the gains as we did on Edges - there would be too much of it. And it’s going to be all white if we don’t put a colored knob for the attenuverter? Ok, let’s use turquoise for the attenuverter, even if it doesn’t make much sense.
At this point it went downhill. For example, in Clouds’ original design (Aeons) - the 3 knobs on the left were related to recording (fuchsia), the ones in the middle to playback (turquoise), the ones on the right for mixing and post-processing. The knobs kept their color in the final version while the module performed a completely different function!
The first wave of utilities and plumbing modules (Shades, Branches, Streams) only had 2 or 3 channels, so colors could be used to distinguish channels - at the risk of causing an inconsistency with Frames or Edges. With more quad modules (Veils and Blinds), should we really have added a fourth color?
And what to do for Rings? A proto used turquoise and fuchsia for FREQUENCY and STRUCTURE, how silly! At this point I gave up and decided to use only white knobs.