Jesse Thorn on why the clothing you wear matters:
Clothing is a way we represent ourselves to others. This self-representation couldn't be more significant. When you dress, you are making a statement; not a fashion statement, but a statement of identity. If you put on a jacket and tie, for example, you are signifying to others that you take the occasion seriously, whatever that occasion may be. If someone looks at you and interprets how you dress, they are not being superficial. They are reading the message that you wrote. If that message says, "I am to be respected," then they will respect you. The language of clothing is as complex as the spoken word, but ignorance of it is no excuse. Can one earn respect in other ways? Certainly, and one should. But that's no reason to open a conversation with someone by saying, without words, "this is not important to me."
Taking pride in how you present yourself and doing so appropriately for the situation you're in isn't silly or vain, it's a declaration to others of the respect you have for yourself and the occasion. That doesn't mean overdressing - that can be just as silly as underdressing - it means there's value in having a sense for what's appropriate and cultivating personal style.