Quote Originally Posted by M. A. C. Newsome
In short, all we really can tell from this statement is that the cheif of the clan wanted the men fighting under him to all be outfitted in similar colors when on the field. It was an early attempt to enforce some uniformity in military dress, and for that reason is important.
That's why hockey teams wear team uniforms. When in close range, swinging a claymore it is convenient to see your "team mates" easily before a slash, right? Wearing same colors is the best way to recognize the friends in fast battle situation. I don't think there is any actual "uniformity" reasons in that.