Walter Isaacson's anticipated biography of Steve Jobs has a few excerpts explaining why the founder of Apple wore his famed black mock turtlneck and blue jeans combo.  Jobs realized how Sony in Japan had its employees wear a uniform to create an identity and therefore, a bond with the brand. He contacted the same designer of Sony uniforms, Issey Miyake, to design a vest for Apple employees. It didn't quite work out the way Jobs wanted, as he told Isaacson, "Oh man, did I get booed off the stage. Everybody hated the idea.”

Even though Jobs couldn't convice his team to wear one look, he decided to wear a personal uniform anyway and had Miyake make hundreds of black mock turtlenecks he already liked. He told Isaacson, "“I have enough to last for the rest of my life.”