Well it's clear from this and the "diaspora" thread, that a certain percentage (of unknown size) of native-born Scots resent, frown upon, or at best grudgingly tolerate the wearing of the kilt by "outlanders."
Taking this mindset to its logical extent, Highlanders should resent the wearing of their native garb by Lowland and Border-region Scots. It is, after all, "Highland Dress" and for centuries leading up to the early 1800s, the latter two groups disliked and mistrusted the wild Highlanders with their strange tongue and outlandish clothing - and none would have been caught dead in a kilt!
Since the mid-1800s, as we all know, the Highlanders' distinctive garb has been co-opted by these same Scots who previously despised it - and we are now witness to Lindsays, Scotts, Bruces, Hamiltons, Cummings, Armstrongs, and so forth strutting about in kilts in their "clan" tartans, when these folks are no more members of Highland clans than my maternal ancestors from Sardinia are!
My point: a unique dress that evolved in a limited space and time - the Scottish Highlands - has long since spread well beyond those narrow confines, travelling by leaps and bounds to many other locations around the world, clung to mostly by those of Scottish descent, but not exclusively. The horse has left the barn! Kilts - like bluejeans - are global, and native-born Scots should accept the fact....