The effect of different paint designs on frame appearance

[pigman]

Now how did we end up with black matt and grey and all the variations between these two colors to be considered desirable nowadays?

If you ask me, this is more of a top down decision by bike marketing "specialists" of mainly big brands and (I am certain of that) not of what most people would consider a nice color on a bike as such.

I think the way a bike is seen has changed. Back in the day it was about colours, paint jobs, chromed bits. In other words, style and beauty played their part in bike design.
Today a bike is seen as a piece of scientific kit, designed to maximise performance. The more monochrome it is, the more it looks like some spaceship in one of those dystopian sci-fi films and hence the more modern it looks with the emphasis on cutting edge science