I so agree with many of the comments about folks trying to "publicize" perceived injustices by the airlines and garner sympathy against corporate giants. Flying is a privilege and not a right.
Yes, there are T&Cs that are agreed to and I for one do get upset when I do not believe these have been followed (and have asked for advice on FT for some of the situations)
but when it comes down to it the airline does not make me fly with them and I have choices.
If I want to sit with my family then I should pay for that privilege and if not, then I can usually wait 1,2,4 hours until we reunite at the end of the flight. Most people are understanding about swapping if there is a small kid (I for one do not want to sit next to someone else's child) but no one usually rearranges themselves when there is unassigned seating for example on a bus or a train - you sit where there is a spare seat.
If I want to take carryon but do not want to pay for the privilege of ensuring it does not go in the space of the foot well then again pay or be satisfied with the situation.
This sense of entitlement (and glad these stories are in the DYKWIA section) is partly why we have these confrontational experiences when flying these days. Sadly. FAs are there for safety - end of story. My goal when flying is to get safely where I am traveling.
If I want to be able to have my own way then I need to pay for the privilege or better still buy my own aircraft (last comment is tongue in cheek as I have no intention of buying an aircraft).