People live for a cultural experience, to learn something about themselves, throughout the human journey. Fashion is indispensable in this voyage.
What we wear (consciously or unconsciously) is usually the way of expressing ourselves, from the simple human impulse to communicate and express feelings to the most extraordinary manifestations, such as events of emancipation or any rebel (as some people want to be seen as the rebels).
It just depends on the public point of view of the specific subculture group. People want to belong to specific subculture, with the same style, to feel like they’re not alone. When you see how fashion touches people, you’ll find out a lot of expressions.
So, what more can you ask from art?
I do reckon that fashion is an art since the oldest human civilization started to exist, where the application of embroideries were artistic expressions inspired by Imperial China.
So, when we’re talking about art, I think (with no doubt) fashion is a part of it! Fashion is a part of life.