I recently spoke to a friend whose brother-in-law refused to wear a tie for interviews, because he was a computer programmer and programming is a casual-attire industry. He believed that to look like he would fit in, he must dress casually.
He has been out of work for three years.
Dressing up for an interview or for a meeting with a client shows respect for that person. Even casual clothing industries expect people to dress up for an interview.
This includes non-profit and artistic organizations.
Courtesy of Culture and Manners Institute