The whole point of not giving you more color options is that Apple force the market to dress up their products.
Look at iPhone, how many types of cases you can get? When the MBP and MBA are popular enough many manufacturers will come out with cases or skinning.
On the other hand, if you have colors on your MBP or MBA, and you want to sell it. The buyers will go "damn this is THE spec I want but I'm not getting yet another black laptop damn it!". Even if it's just black and white. Color preferences will affect at least a little on the sales of the 2nd hand market.
Skinning or thin cases perhaps still the best way to go and you can always change it when you change your mind after some time, and they'll protect your laptop at the same time.
PS: If I sound ignorant, I most probably is.