Scotland's National Attire

[CMcG]

I know the kilt is Scotland's national attire, but I'm curious to know a bit more about this fact from a historical point of view. I'm thinking particularly in regards to the level of acceptance of this in Scotland generally, as I understand the kilt's origin is as the regional, ethno-cultural attire of Gaelic Highlanders. I'm not necessarily asking how many people wear the kilt or how often (a question that has been asked before), but rather if all Scots accept the kilt as their national attire, regardless of whether they own one or not? That is to say, how much is the kilt a part of modern Scotland's heritage?

I think I've read on Xmarks that as recently as the 1950s, a Lowlander wouldn't have been caught dead in a kilt. Is this true and if so, when and how did this change? In other words, do all parts of Scotland accept the kilt and to what extent?

I've asked another, related question before, but never had a clear response: does the kilt have any official, legal status or is it more a question of culture and common practice? Perhaps this question could be complicated by Scotland not being independent, but rather being a part of Great Britain... let's try to not make the answers political so this thread doesn't get shut down, eh?