Keith Blount, the brain behind Scrivener (one of my favorite pieces of software), talks about The Mac Monochrome Trend – A Plea For Keeping Things Colourful:
When Apple decided to drain the icons in these programs of their colour, I learned something about the way my brain works that I hadn’t hitherto ever had to think about: my brain is an awful lot faster at processing colours than it is at processing shapes.
I’m the same way. I use a mix of 10.6 and 10.7 machines. When I go back to 10.6, I’m reminded how quickly I recognize the sidebar icons in the Finder, and on 10.7, it’s all a gray mass.