Aesthetics communicates and fashion is very much about aesthetics. The other thing about aesthetics is how individual it is. Music and art preferences, colours and the clothes that are worn are very much a communication of individuality.
So its really surprising that there is enough uniformity to create niches that can be marketed to. The thing is, to tap into and find the agreements that define a niche. People who are part of a particular group have made agreements in order to remain in communication with other people, if there were no agreements there would be no friends