I think you have to consider what lies within the "spirit of tradition" versus simple non-conformism or contemporary styles. Tradition implies a long standing way of doing things. Contemporary styles of kilts, such as utilikilts and their ilk are hardly long enough to have formed a tradition, but are instead at this point a style of fashion. Whereas 4-yard box pleated kilts are a tradition that has been revived and has gained more acceptance lately.
Things such as white kilt hose, tartan flashes, flat caps, and their ilk, while not traditional to Scottish national dress, do fall within the "spirit of tradition" rather than outside of it attempting to do its own thing. Those things are more modern styles that are appealing to the dress' Scottishness. Whereas most contemporary styles of kilts are not Scottish and don't attempt to be, but rather appeal either from a sense of comfort or style on its own supposed merit.
Honestly, I think comparing contemporary kilted fashion with traditional Scottish attire and modern Scottish attire is problematic as they don't blend well and aren't really all that much related. If it weren't for calling them all kilts--which is only done because of rear pleats, we could be just as obliged to throw sarongs in the midst of the discussion.