You <------> My point
Simply put; what is so difficult about not adding excessive charges to passengers? And why are you trying to justify this?
Then pay more for an airline that provides that.
The RyanAir deal is pretty straight-forward: you will be treated like subhuman cattle, and in exchange you will have very low prices. They optimize many things to save costs, including having less staff for things like printing boarding tickets. They're fairly up-front about it and in general it's a fair deal. Whether you personally like that deal is a different matter.
I don't know if that design is around, but they would have the option to add extra carry on (not luggage). The image would be of something that clearly looks like luggage, and next to it a tiny tiny backpack.
If you read the wording carefully, you'd notice that this is just for carry on. You have to scroll down to the bottom of the page, select a submenu and there you can finally see the option to add luggage. That's straight up scammy.
I've never been treated like a subhuman on Ryanair. I have been treated like cattle.
That does not mean it is acceptable.
Treating passengers in a respectable civilised manner should be a given. Quite why we have sunk to thinking such shenanigans are acceptable will continue to puzzle me. If any other business tried this, you would tell them to swivel.