It is blindly obvious you are paying for the travel from point A to point B without luggage. Carry on and free baggage are only a convenience. "The advertised ticket price is the *only* thing the airline should be allowed to charge you for your seat, baggage (checked or carry-on up to a regulated size and weight), and any additional services offered to you during booking, in the airport or on the plane." which would lead to airline making sure that it is blindly obvious that you are not paying " it is ALREADY blindly obvious. Which is why for all big carrier I know of for big alliance (one world, star alliance) you are not paying for luggage, you are paying for excess luggage. That may be different for discounter like Ryanair but it is not the case for standard carrier. Heck the things is called an EBT (as in "excess baggage") or used to before the advent of EMD (electronic miscellaneous document).
"It's also high time that overbooking or fuel surcharges were banned, as well. It's not like the airline refunds you a portion of your ticket prices when gas costs less than expected, or refunds you if you decide not to travel on a ticket you paid for, so what possible reason is there for them to be allowed to raise the contractually-agreed price after you've already paid it or to sell your seat to somebody else as well and hope one of you doesn't show up?"
Firstly you do not pay AFTERWARD a surcharge. You pay it at the moment you pay your ticket and it is included in the price. The things is often the reservation is separated in time to the payment. All fee, services and tax are calculated at the moment you PAY, not at the moment you reserve. And it is quite clearly indicated normally when you book, except a few airline which advertise they guarantee you a price at reservation. And the contract is not "signed" at reservation by the way it is "signed" at payment. Which is why for example you can do a res , and then simply say "screw it I am a noshow" and thus making sure the airline has to overbook or get screwed with a non saleable place and thus loss of money. And do not get me started with double booking by some people (cheapo tariff and normal eco tariff, if they get the place in the cheapo one they simply refund the normal tariff).
"or refunds you if you decide not to travel on a ticket you paid for"
You actually get a refund for tickets you do not travel. Depending on your tariff it may be partial, full, or minimal. That is why you can get a cheapo ticket : you forgoe the ability to get a refund or free rebooking. Want to be able to refund ? Then stop buying the cheapest tarif and get the normal undiscounted tariff.
"Sadly, there's zero chance any of this will ever happen" There is no chance that will happen because your post is based of a totally erroneous understanding on the reservation and ticket sale process. Why this was modded insightful is a wonder.