I would say that if you're going to wear brown leather, make sure your hose and shirt coordinate. A tan shirt would be in keeping with a pseudo-military style, and make the brown leather work. However, if you went with a black shirt and hose, the brown leather would look completely wrong.

I have two Black Watch kilts, and I only own black leather accessories, but the two don't necessarily have anything to do with each other. I own black leather accessories because I like black leather and don't like brown leather, and I own Black Watch kilts because that's also my clan tartan (Campbell).

Wear what you want. Treat the kilt like you would pants. Make sure your colors coordinate or compliment each other, make sure your leathers all match, and make sure the outfit as a whole works. If you've done that you're good to go in my book.