It's not just about adaption, looking good/trendy is about first impressions and signaling that you'll fit in with the "cool" culture at a certain company. I've known young people who dressed badly not do well either, and I've often counseled them to make some effort with their appearance and it makes a huge difference, even very little things like buying shirts that fit or paying money for a real haircut. We'd love it to be a pure meritocracy, but at the end of the day what you look like matters to other humans.