"Balmoral" Doublet Help?

[CMcG]

I also can’t get my head around people saying that a jacket like this should be worn/can be worn unbuttoned to "black tie" events. It's already been explained to us over here that black tie has a different meaning in the USA, ( and now, apparently, also Australia), but I still can't quite get the "unbuttoned" business.
I am asking this because this thread is in the “traditional” section: This jacket is designed to be worn with a belt over the waist, so why would you unbutton it?
Would you take the belt off?
Or would you just not wear a belt with it?
If the latter, then why not just wear an Argyll?

The idea for wearing a Balmoral doublet open for less formal events, came from the Highland Clans retail website where they say "It can be worn less formally unbuttoned - in this case the belt would be worn round the kilt (under the jacket)." Thanks to Jock Scot's explanation, I think they mean less formal than white tie/full dress, but still black tie formal. Here (again) is the link to their page:
http://www.highlandclans.co.uk/Balmo...t_Doublet.html

If the latter, then why not just wear an Argyll?

I already have an Argyll jacket (some might call it a Braemar because of the flap cuffs, rather than gauntlet style) and below is a picture of how I wore it to a Burn's Supper here in Hong Kong. The Balmoral jacket was purchased because it was inexpensive and I like having options:

Even with an Argyll, where would you wear one “unbuttoned”? I am looking right now at the programme/menu of the last formal function I attended, there were about 150 kilted men present, mostly in black Argyll's but two of the "Old & Bold" were wearing Sheriffmuir Jackets with belts over the top. (We are talking about two men in their late 80's here, and that's their understanding of evening dress, from their time period).

After supper, in print, permission is given to “loose a button”. As it was a big dinner, that’s understandable. There was then a medal presentation and an MSR from a piper. Buttons were then firmly back in place for the official toasts, the Queen and the Regiment. I'm no expert on sartorial correctness, I'm just a scunner from a cooncil hoose that dis' fit he's telt, but I've been doing what I'm told in the name of tradition for a long time.

Why and where would “unbuttoned” suit a formal occasion?

In real life, I've never seen anyone button an Argyll jacket, either tweed or black barathea. On Xmarks, I've seen countless pictures of Argyll jackets being worn unbuttoned and only very rarely buttoned. I have been told by people more knowledgeable than I that unbuttoned is the way to go.

I'm no expert on sartorial correctness either and certainly don't have as much experience as you... are we talking about the same jacket?