I needed to digest all that !

For revenue passengers in North America, I would disagree.
They have been spoilt for years. I can't recall seeing as many people approach a gate agent asking for an upgrade as I have seen in North America.
Want to sit in C class - buy a c class ticket.

I have seen, on not one, but several occasions, passengers arrive from a ORD flight into a European city and approach another airline asking if they can pay for an upgrade to C class.
The response is, " sure, recalulate the fare and that's 2,000 Euros ... " WHAT?! " I just paid $500 and travelled c class "
' Yes, North American carriers are trying to generate instant cash and offer a fixed price upgrade, unfortunately, we recalculate the fare ".
Take away that cheap upgrade and see how quickly that passenger shows their loyalty if another carrier offers them the same - even if they have to jump through 3 connections !

The other point you make regarding travelling on your own airline is very valid and another angle to take into consideration.
I would imagine that many airlines charge based upon the class of service they wish to travel, or deducted from their payroll after the event, as is the case with us too.
However, if you had a Y class ticket on another carrier and they seated you in the C class cabin, would you angle, ' No, I paid for Y class and Y class it should be ' ?????

The hotel upgrade policy I disagree with.
Airlines are amongst their bread and butter for crew. Airlines have a daily allocation, spend good money at major chains - when they are experiencing their lean period, those crew rooms are still being occupied. So I say THAT's loyalty !

During the 9/11 period when the general public feared flying for a demonstrative period unless they needed to, airlines still required crew to operate the flights and the same airlines took the same number of rooms as they did on 9/10 !

All I can say is, if I were a gate Agent , regardless what fare you paid, if I had the opportunity to allow you C class travel, I would not hesitate - providing you were dressed accordingly and smiled ..... I would hope that upon your return you would tell your colleagues, who, if they were in a position to do the same for me, would.

I'm not implying that the expectation is to buy an interline ticket in Y and expect to travel C, if a C class facility is there, I pays my money for C ... but, at a gate situation, where only C class is left ..................