Huh? There's nothing inherently monochrome about emacs or vi/vim. Both support colour syntax highlighting, and I'd be surprised if the vast majority of programmers using those editors weren't using it. Certainly everyone in my workplace who uses vim (including me) does. (Don't know about Acme).
All great monochrome editors.
Plenty of exceptional programmers use mono. One wonders if it is a cause or an effect.