Times change, but I think that some older habits weren't bad at all. Could be that I don't relate those things to the actual clothes of people, but more to their overall behaviour, the respect towards others, also some tolerance.
If at high levels of course, no one would appear like your example guy in public transport vehicle of any kind.
But if a thing, which was a former highlight of guy's life (flying was a thing of the rich and famous), becomes more regular and cheap, so do the people. The industry works hard to establish flying as the cheap and accessible transportation solution, even over buses and trains on shorter hauls.

I wonder what a stewardess could tell about the changed people's behaviour then. Ask one who does the short routes to certain party locations for example.
Seems like some things in our worldwide societies drives us into impolite and rude regimes, sometimes. The bad thing, some of us don't even notice it anymore.

But, who knows, maybe your first class fellow was some sort of rock star or just the younger Bill Gates.  ;D
But your engagement there showed quite some guts. You can only do this when knowing that the company supports you, the employee, in the first place. Some may fail there nowadays. That's bad manners too in my eyes.