I still think that they aren't really copying apple. Nokia really started off the whole mobile customization craze with faceplates. I think that all these companies offer similar colors because market research has shown these are the colors people want. If surveys show people want blue, pink, black, white, green, and orange, companies aren't going to say, well company x already made covers that color so screw what people want, we are doing yellow, red, purple, and silver. They say, if these are the colors people will buy, these are the colors we will make.
For the record, I'm all about red cases and in the highly probable event of my buying a surface, red will be the color of my touch cover. A big thank you to Microsoft for choosing the often neglected color red.