I think this approach to color selection is a wee bit patronizing, assuming that all users are the same (and gives waaaaay to much credibility/authority to graphic designers). Never mind that even if you agree with the intended choice, you'd need to make adjustments to cope with environmental factors (displays, light etc.).
It was really a marvelous email, polite yet firm and a crystal clear explanation of his philosophy. Over the years I have from time to time spent hours trying to find a copy of that email. It is lost.
But I can say definitively, both as a matter of philosophy and because I did the lion's share of the open source release work for both systems since color went in, that there have never been color theme files in the Plan 9 distribution, nor in plan9port.