First let me say that I realize that kilts are a little out of the everyday experience for most people. To that end, I usually don't wear one when working corporate jobs (though I tend to ask what ever production company I'm working for how they feel about it). I can actually dress anywhere from jeans to a suit.
So why a kilt? I had worn a formal kilt to dress events for years, partially out of honoring my heritage, and partially from just trying to stand out of the crowd a little. Then in 2001, I heard about Utilikilts. I thought they were cool and decided to get one, thinking that I might wear it to concerts and the occasional festival.
The first thing I discovered is that they are incredibly comfortable. They are much cooler or hot days, and allow a better range of movement. This translated well to doing a shoot since I could now work a 12 hour day and not be sweaty, sticky and chaffed by the end of it.
The second was how practical. The cargo pockets allowed me to carry more of the junk I need for production (and in better locations) than any pair of cargo jeans or shorts. For instance on a recent run and gun shoot, I had one pocket filled with extra batteries and tapes, while the other held the wireless receiver and I had an XLR cable coiled and hanging from the hammer loop. While I have done the same thing in jeans, the loose pockets of the kilt kept everything from being awkward.
Third, is the good luck factor. Now I'm not superstitious by nature, but all of the films I have worked on kilted have been completed (Disclaimer - one is still in production and one should be finished with post soon). On the other hand, films I've not worn a kilt on have only a 66% completion rate.
Finally, it does make me a bit noticeable. Everyone knows I'm the guy in the kilt. Frankly, a little extra publicity can't hurt.