I find concept of something being "fashionable" quite puzzling. Why many people feel obliged to wear "fashionable clothes"? They don't wear it because of aesthetic value - or do they? If something was fashionable last season and now it is not, does it mean that the aesthetic judgement changed or do people recognize value in conforming to the majority?
The answer is simpler than you think. "Fashion" is the effect, not the cause. Combine two separate concepts: First, that pleasure resulting from a certain aesthetic fades over time. So yes to your first question, it is the aesthetic value that changes. You can only eat ice cream so long until you get tired of eating it, even though nothing changed about the ice cream. Similarly, people get tired of seeing the same kind of clothes being worn all the time. There is a certain pleasure in novelty.
Second, fashion has a social value, as well as an individual one. Socially, what people wear is a significant part of our environment, so it's more pleasing to see people well-dressed. Individually, to wear clothes that other people find pleasing arouses our vanity, so we have a personal interest in pleasing our society.
"Fashion" refers to this careful equilibrium between social pleasure and individual vanity.
Of course people recognize value in conforming to the majority, even generosity is punished for non-conformism , but more important than that, people recognize value in arriving early to the trends. Arriving early to trends means two things:
- conforming to the majority in the future, which is obviously better than conforming to the majority in the past.
- being one of the first people to arrive to that majority, which means being a leader, an example to follow, etc.
- if there is some pyramidal effect, the difference is even greater. Think about the economic bubbles, the first people to join the hype get rich, the last ones go bankrupt.
It's more of a sign claiming "I'm up to date" than any aesthetics, but being up to date is very valued by many people, even if it is about something as irrelevant as clothing and even if being up to date about irrelevant things implies an opportunity cost and means lost opportunities to be up to date about relevant things. Subconscious thoughts are not characterized for being very deep.