Lopy I understand not wanting to have too much color in the UI for perception purposes.
I understand it if you're a big commercial company that needs screenshots to look good, like a decent poster for a bad movie. I understand this is how something so rediculous as flat monochrome icons (no matter the total amount of icons) can become an industry standard. What I don't understand is how people prefer it after the experience, without having it shoved down their throats at school/work; how this "standard" can be adopted by all major FOSS, with people retorting "you'll get used to it". Monochrome icons take twice as long to find, which gets worse with a bigger haystack. Making everyone colourblind is not how you're supposed to handle accessibility. In many cases it is simply appalling design.
If the argument is that someone is too professional to handle the colour clutter, my question would be how they can be so professional without knowing enough shortkeys to do without a toolbox altogether.