You don’t have to be Scottish, or even of Scottish descent. If you are wearing the kilt with respect, and not as some kind of joke, it is a comfortable, flexible, and stylish addition to your wardrobe.
A properly-worn kilt is the secret weapon in a man’s wardrobe. It can be worn as formal attire (with proper jacket and accessories), dressed down from semi-formal, business, casual, and on down to a t-shirt and sneakers—all with the same kilt. No item of men’s wear has such versatility.
I’ve worn mine (I think I have 7 of them, of varying weights and tartans) to work, weddings, hiking, dates, religious ceremonies, grocery shopping, walking the dog, you name it. Always had a positive reaction or curiosity leading to a pleasant conversation. The occasional boor who shouts out “nice skirt” or the like is usually some dolt with his pants falling off his butt or equally ridiculous fashion choice of his own.
If you are interested in adding a kilt to your style, there are a variety of options, ranging from the high end (tailor-made, 8-yards of heavy wool, family heirloom kilt you will pass on to the next generation), through lighter weights of wool (and lower prices) down to very respectable polyviscose/synthetic blends for $70–100.
I had my “family war kilt” made when I visited Scotland in 1992 when I was 20. It wasn’t cheap, definitely beyond my college student budget, but it shows no sign of wear or tear decades later. (I mostly wear it for the most formal of occasions now.)
For daily wear, to work, even hiking and camping, my go-to kilts were made by www.stillwaterkilts.com— one in Black Watch (the commonly seen black, green, and blue tartan) and another in McLaren—that cost about $100 each.
(Personal preference, I am not a fan of the non-tartan “Utilikilts” made of cotton, denim, leather, etc. I’m a plaid man.)
The only times it is “out of style” is when worn improperly—hanging past the top of the knees (an unforgivable crime against all that is right and good in the universe), wearing inappropriate attire and accessories for the level of formality (just as it would be to wear a pair of shorts with a tuxedo to a wedding), or worn backwards (seen it done a few times!)
Wear it with pride, confidence, and a glint in your eye. What other item of clothing can bring women you’ve never met to come over and ask you if you are wearing underwear?