Many years ago, long before Australia even had a place in my life and I knew anything about FF status, I flew London to Frankfurt on a Friday evening - too long ago to remember which airline. Having gone straight from work I was still in my suit. As we were queuing to board an airline employee walked down the line and asked 5 of us to stand aside and we were then asked if we minded moving to business, and not surprisingly none of us minded.
But it was easy to spot that among the folks queuing up we stood out being the ones who were dressed 'professionally'.
That said, if I was to be getting on an aircraft I'm always going to dress for comfort rather than for the slim chance of winning the upgrade lottery.
I do think that 30 years on from that initial upgrade, loyalty programs play a more prominent role and any upgrade today is more likely to be due to status than a suit. Nowadays as WP I have had the odd upgrade, and as somebody who always travels down the back end, it's always most welcome.