I agree with you in that one. We should also remember that emos and darks appart from their style they have a philosophy, a lifestyle. From what I know emos and darks wear black and they reflect on the sadness and their inner nothingness of life (that for them life's not worth living). They mostly listen to the bands My Chemical Romance, Tokio Hotel and Good Charlotte.
In May 2008 Hannah Bond, a 13-year-old girl from Kent, hung herself, and Emo music was blamed for her suicide. The coroner suggested that because Bond was so obsessive with that music that it was linked to her death.
I agree we should wear with light colours cause dark and emo clothes as their hearstyles reflect their inner sadness and negative perspective about life, and when you wear that it makes you feel that way. There are certain clothes, hairstyles and music that makes you feel that way.
So all in all, clothes and hairstyles can affect your life and who you gather with, your group of friends, etc.
So, you need to be careful cause the Bible says that “I have the right to do anything,” you say—but not everything is beneficial. “I have the right to do anything”—but not everything is constructive. 1 Cor. 10:23