There were two reasons for the robes, one you were honoring your guests and making so even the ones who were not wealthy could attend without shame, the second was that it was a really popular pass time to attack wedding parties to rob the guests and carry off the bride for ransom.
Wearing the robe meant you were invited and honored.
If you did not want to wear the robe you were spitting in your host's face and breaking security.
I’m not a great Biblical scholar ... I just learned that 3 days ago.