"Well, you'd get to order off a long menu instead of accepting set meals," you'd explain. Really? asks your hypothetical friend from the future. Like, you do in any crappy restaurant? That made it worth it? "Oh, but this was really good food!" you'd insist. Your friend rolls their eyes. If you're into food, you could have bought dozens of meals much better than anything the plane offered for the extra you paid.
You'd next say, "Yes, but first class also offered extra legroom!" And then, seeing how this doesn't at all impress your friend, who is sitting on a park bench and has infinite legroom for free, you add, "And then in the really expensive flights, they'd let you lie down FULLY FLAT!" This only confuses your friend, who knows a bit about 21st-century life. They know ramshackle trains in developing countries let people sleep fully flat, and tickets cost only a few dollars each. They know the cheapest hostels in the world let people sleep fully flat. How was sleeping flat considered a luxury?
"Because those hotels and trains weren't FLYING THROUGH THE AIR!!" you'd insist. But that doesn't convince them. Because they know that simply flying through the air could cost one-twentieth of the first class price.
As with everything we're talking about today, I'm not trying to convince you you're dumb if you want these things now. Offer me a free first class ticket, and I'll grab it and have a great time, not scoff and say I'd be equally comfortable in the overhead bin. I'm just saying the time may come that the inconveniences we now barely notice will appear so great that comfortable slippers and a deluxe top hat will do nothing to make up for them. On the other hand, not all kinds of flying will lose their charm to the people of the future ...