If you work a 9 to 5, fashion is important. People do judge you by what you wear. If you show up to a job interview looking like a hobo, you will not get the job. If you walk around the workplace dressed like a hobo, you will be judged negatively.
People judge you based on your appearance, and you must conform to their expectations if you are dependent on them.
If you need your salary to pay the mortgage, the car payment, the credit card, the student loan, and the school fees, you have no choice but to conform if you want to maintain (and grow) your salary.