In my experience, many men would prefer to dress in polo shirts and chinos - or other comfortable clothes (I love the Garanimals comment). One of the things that I remember about the military is that it specified EXACTLY what was supposed to be worn to any given event and DeHubby HAD to wear his mess dress (tux equivalent) if that was the "uniform of the day".
Many women (but not all) prefer to feel that they are dressed correctly for an event. Having a level of formality spelled out to be comparable with the "uniform of the day" meant that I never had to worry about being SERIOUSLY underdressed or overdressed. Although when I was active duty myself, I just wore MY "uniform of the day". DeHubby and I always "coordinated" that way!
Using an essentially meaningless term, such as "festive" makes understanding what kind of clothes would be appropriate even harder to sort out for most of us.
I have worked in "business casual" office that had occasional people show up in outfits *I* personally found deplorable - turquoise leather pants that were tighter on the wearer than they had been on whatever animal the leather had come from comes to mind. As did several outfits that required slits to allow the wearer to walk "normally" instead of gliding like Morticia Addams..........slits that went further up than coworkers NEEDED to be seeing, in my not-prudish-opinion.
When a VERY important person came for a major event (opening of a new building) - we were told to wear "business traditional" clothing for the two days that *Big Name* would be around.
It was mid-December. I saw velvet skirts and jackets with satin blouses, satin skirts with lace blouses, metallic knits and lace tops everywhere...........looking back, I might have called them "business festive" if I had been asked to characterize them. I wore a plaid cardigan styled sweater styled very similar to a Chanel jacket over trousers with rubber soled loafers that matched the pants and a knit shell with tone-on-tone embroidery that picked up the accent stripe from the plaid. My outfit had no lace, velvet, satin, bows, sash, metallic accents, pearls, little bells, sequins, beads, or other "accents" - which probably 60% of the other women were wearing............the entry level personnel had a looser grip on the meaning of "business casual/business traditional" than those who had been working at the company for fifteen years or were working at a managerial level or as supervisors.............
I suppose part of the problem *might* have been that the younger people working at the entry level just did not have either the knowledge of what kind of separates made for a more versatile wardrobe or had not been working long enough to accumulate a wardrobe with a wider range of options........