Shiny Primer

Most rich colors show dirt, scratches, and damage far more readily than white, silver, or grey. Black is horrible when it comes to upkeep, and metallics are a pain in the *** to repair. Add to that all the shitty clearcoat OEMs have used for years which make everyone equate darker colors with peeling paint.
I think these are the reasons your average car buyer gravitates toward muted colors...

Personally, I think grey can look good with the right combination of stripes or accents, but is otherwise worse than 'camry tan'. Then again, I will also never own another black vehicle unless I can get it so cheap that I can repaint it. I hate the upkeep that comes with black. So many swirl marks.