Chrome and mirrored polished surfaces started diminishing within the realm of consumer products back in the late 70's and 80's. Chrome finishes became harder to produce, because of the new environmental concerns surround it. Polished finishes were directly linked to the labor required to obtain them. So, silver and black finishes started to ebb there way into the arenas where chrome/polish had once been... automobiles, furniture, electronic consumer goods, etc. Black, always associated with formality and culture... think tuxedos, cocktail dresses, and Sunday shoes, seemed like a likely substitution choice.

I also think that our society is more market research driven now, and trends created within a market research environment tend to be self fulfilling. When Ken Consumer buys a black component bicycle, market research trends that to "Ken Consumers LIKE black component bicycles", and given that somewhat misread conclusion, the manufacturers gear up to make even more black components for bicycles. It takes someone who understands the consumer better than it understands itself, to break away from an entrenched trend. Case in point... I remember reading an article from around 2007, in Bicycling magazine, comparing 5 bicycles in the $1K cost range... each of the competitor's bikes in the comparison had dull flat finishes with white/grey/red logo schemes.

Black is a very hard color to match, sheen wise, and thus, I think the "it's scratched... and looks used" design obsolescence argument has some validity.