While the concept of fashion may initially connotate art and beauty, modern fashion is a conformist statement. It is no longer an "expression" of self, as practically all the fashion is the same. Sure, there are slight variances, but they all speak the same personality, same thoughts, and same concepts.
Not to mention, the current fashion industry belittles average people, destroying their self esteem.
Fashion damages society by psychologically forcing people to attempt to meet certain standards that are artificially set by the media and corporations. Individuals are taught if they don't buy the latest fashions, attain the trendy body type, consume the trendy foods and watch the fashionable shows they are societal misfits. Many tests have shown, both men and women are marginalized in social settings if they can't afford to wear the latest clothes, losing jobs to better dressed individuals and being treated more rudely than their more fashionably styled counterparts.
Fashion is a form of art and expression. Because of their innate love for beauty, human beings will always strive to create beautiful things, including beautiful clothes. Therefore, fashion in itself is not a bad thing. In fact, the sight of well-dressed people is pleasing and uplifting, so society is rather bettered by fashion, not damaged. Some people's decision to make it the highest value in their life is the one that can damage them and the society. However, people have the right to refuse to follow the dictates of fashion, as being fashionable is a choice.
Although fashion can be vastly overrated and even become an obsession for some, it does not damage society. In fact, fashion is ultimately irrelevant to society. It does not add any value to societal construct. It is simply a way of expressing self through clothing, much like art and music are forms of expression.
Presumably since the creation of clothes, there have been designers and wearers expressing themselves with their clothes. The right shirt can show off how a person is feeling. The proper pants can make a person feel apart of a group. Fashion has oftentimes shaped different societies' cultures, from the bell bottoms of the disco era to the leather jackets of biker gangs. The different combinations of fashions make each individual unique.