I realize I'm new here, but I have one or two things to respond to, having worn a great kilt weekly for ten years.
1) It's cumbersome and difficult to wear.
Admittedly, it takes a bit of practice, but when folded properly, I'm far more likely to get my cold weather coat or suit jacket caught on things than I am the folds of my great kilt. I've done everything there is to do, from stage fencing to yard work to Broadway dance rehearsals in my great kilt and never had a single incident of ripping or inappropriate slipping.
2) It looks "costumey" or too "period."
This depends on your skill, frankly. If you can't make straight lines or properly estimate your body width, you'll end up with some of the blouse-y, hideous looks that I've seen in many pictures. This did tend to look like a period costume. The way I tend to wear mine, I have frequently been asked by other kilt wearers if I'm wearing a great kilt or just a regular kilt and a particularly ostentatious fly plaid. Admittedly, the folks on this forum would readily see the differences, but my point id that it is completely possible to create the same clean lines of a tailored kilt if you're very careful and precise. And this, including the pleating process, I have down to about ten minutes.
I tend to wear mine with a simple black waistcoat, and french cuffed shirt, with a thin scarf of the dame tartan tied as a cravat. Avoiding the "jacobite shirt" or any other non-modern (or completely made up) accessories also minimizes the costume element and helps people to see it as a modernization of a useful and versatile garment from the past. I find that it's only as "period" as you accessorize it to be.
On the other hand, in my day job I frequently switch between 18th-century Spanish soldier, 8th-century Chinese courtier, and Russian boyar from the era of Ivan the Terrible all in one day, so take my fashion sense with a large grain of salt.