I've flown some 20 commercial flights in the last year and never faced any of the issues you've described. I find flying quite fun to this day. Perhaps this is highly regional.
When someone tells me to arrive 3 hours before my scheduled departure time, to me it's disrespectful that they would waste so much of my time so unapologetically.
Other people might see it as no big thing, an enjoyable chance to sit and read, or do some people-watching, or a comforting safety margin.
When someone tells me to take off my shoes and belt and shuffle through a metal detector while they take my wallet and keys out of sight, under the constant threat of even more intrusive searches - to me that's extremely undignified. There's no other situation in my life where people can control what I wear, or presume to separate me from my keys and wallet.
Other people might feel reassured by the process, or see it as no different to going to a swimming pool.
When someone demands I walk a needlessly winding path through a maze of tawdry shops selling overpriced perfume, to arrive at an uncomfortable seat surrounded by garish billboards.... you get the picture.
Technically most airlines only require you to arrive 60-75 minutes before departure for check-in. The 3 hour advice is just advice that you're free to ignore, but is probably a bad idea to do so given how much money/time is on the line. The 60-75 minutes might still sound like a lot, but gates typically close 20 minutes prior to departure, and boarding starts 40-60 minutes prior to departure, so they're only really asking you "waste" 20-30 minutes.
>There's no other situation in my life where people can control what I wear, or presume to separate me from my keys and wallet.
courts/some government buildings do similar security checks, and in some countries they do such checks in even more public places (eg. subways/malls/cultural sites).
Thankfully, I lived in said city so we went home and came back the following day. One email to the airline gave us £800 in compensation, plus the cost of our food and Ubers back and forth. Our travel insurance paid out for most of the things we missed out on like the hotel night, events we had planned, prebooked meal, and even our airport parking (which we did technically use). We were done and dusted with it within 7 days.