You can have it in any color you like, as long as it's white!
I am speaking from my personal understanding here, not as a D-Link employee. I wouldn't even personally know D-Link stance on this issue.
Why does it matter to you what color a router is?
Is it considered a type of fashion accessory now?
Does it need to match your décor?
Who all is going to see your router?
Shouldn't physical security be a primary aspect of network security, and therefore only authorized personnel should even see it?
Why must everyone have a macabre obsession with the color black?
Why must everyone else have a perverse obsession with the color white?
Why does there exist a minority 3rd group who insists on anything but black or white?
Why do products sell because they pander to one of those schools of thought? I realize that I have listed all the possibilities, so every product must fall in one of those 3 groups, however I don't see why people care in the first place. I mean why would something like color alter sales?
For the scientifically minded though I will say that white is the color that makes the most sense, as it will reflect the most light, reducing possible heating due to a sub optimal environment (read full sunlight).
<edit>Corrected spelling, I swear I know this language</edit>