At least with Apple the color is through and through. You buy those cheesy Windows notebooks and many have a plating over plastic. When they wear off they look hideous. I remember one HP Pavillion that I had years ago, within 6 months my palms had worn off the plating below the keyboard and that looked horrible.
So it comes down to what the case looks like? Nothing wrong with that, I am just saying... others may be more concerned with the actual performance. I buy plenty of things based on aesthetic design.
Anecdotally, I purchased my REFURBISHED Dell Latitude X1 12" (which is a rebranded Samsung) within a week of my brother-in-law purchasing his G4 Powerbook 12". My Dell saw a large majority of Europe as well a dozen states, and it even spent a bunch of time on stage running Reason 3 with my microKorg as a controller. The Dell looks new, sans one of the rubber feet. My brother-in-law's Powerbook's "trim" has buckled, he is on his third power adapter, and the screen is dimming significantly. Maybe it was the handling; I am not hard on my gear, but I also do not obsess over the appearance.
The Dell still lives on. My wife loves it. It weighs 2.5 lbs and runs Windows XP well for MS Office and internet browsing. It was the original netbook, if you ask me.
The thing about plastic vs. metal; Nikon users talked up how Nikon lenses (used to be) all metal, professional construction while Canon users settled for plastic toys. In the field, though, you learn that plastic tends to bounce while metal tends to dent. Funny. I am a Nikon user for years and still prefer metal builds; they just feel right. I also prefer the aluminum Macbook Pro. It is a preference, though. I would not consider it anything but a preference.