Obviously you did not fly back in the 1970s before the airlines where deregulated under Reagan when it cost $450 dollars (1970s dollars) to fly coach from pretty much anywhere to anywhere else in the lower 48.
After deregulation the airlines are charging about a quarter or less of what they charged then and are constantly flirting with bankruptcy, pushing their unions for concessions and always trying to find cheaper ways to do everything.
What the airlines are doing is somewhat deceptive marketing and somewhat trying to cut cost. Yes they charge you for an extra bag but that also encourages you to travel light which saves the airline fuel.
I even think it would be fair for the airlines to charge passengers by the pound.
It may be hard to believe, but the airlines we deregulated in 1978. It was a broadly bipartisan vote, and Carter signed it.