In the show ring
While showing animals in a show ring setting, you must wear the right attire that is the standard for that discipline. For horse shows, human attire is often laid out for exhibitors in the show standards set up by the show or the breed club. For dog shows it is more based on the current trends and practicality.
For the exhibitor showing a dog in a show, it is practical for the handler to wear semi casual dresses and flat shoes. For a man or boy a semi formal suit would do best. Current trends in handler clothing tend to follow the fashion of the day. That is the fashion set by handlers that are winning at the national level shows.
I have seen some of the most outlandish outfits at the smaller dog shows. I really don't know what those exhibitors were thinking. Maybe their dogs were so bad, conformationally wise, they thought that they would distract the judges.