Perhaps it's a bit of a chicken and egg thing. I'm not convinced that it is the passenger driving this. Airlines want to make money and pay shareholder dividends, so the poorer service will come anyway (it's cheaper than expensive service). The airlines are then competing with each other to win market share. And they can offer lower prices with poorer service, and also new fuel efficient planes.
The airlines are setting the prices, not pax. If full service airlines could get away with high fares and poor service, they would.
Airlines aren't doing us a favour by flying cheaply. They're doing it to make money for themselves.
I have quoted your whole post, but I will attempt to respond in parts:
"Airlines want to make money and pay shareholder dividends". I am sorry if I misunderstand your overall slant, but I perceive you as saying this as though that is a sin. ??? Any company that is not a not-for-profit exists specifically to do this. These are not government services. They are businesses. And as I have detailed before, the airline industry is a hard one, where the profits are very low. Most investors wont go near an airline as they can make far more money out of consumers in other services and products.
"The airlines are competing with each other to win market share". Yet again, this is a basic requirement of any business that wishes to stay alive. For an airline to compete with another, they are fighting for the pax. IE they need consumers to choose them over the competition. It has been proven incontrovertibly (through sheer trial and error) that the number one selection criteria that most pax use is lowest price.
"new fuel efficient planes" - the perpetual fight to stay alive means airlines have to reduce costs in every way they can. Because the margins are so amazingly slim that cost-cutting is the number one focus on every airline in the world. This has in itself brought wondrous benefits to travelers - this is why air travel is so amazingly cheap. Constant, eternal, struggles to make the whole thing less costly. In real dollar terms you can buy a flight in Business class now for the same cost as economy just a few years ago.....
"If full service airlines could get away with high fares and poor service, they would." That is true of essentially all businesses out there. They would like to make the most money that they can. They are not there for your benefit - they are there to make money. Everyone from your local supermarket to Jim's Mowing is in the same lot. That is how the economy works. I do not understand why you consider airlines to be special in this regard.
"I'm not convinced that it is the passenger driving this." If it is not the pax who have the power through choice, then who is driving this? Why would airlines want to drive down prices?? You express that if airlines could, they would charge more. Maybe you should be thankful that it is actually a very competitive market where the consumer does enjoy the power to freely choose.
"Airlines aren't doing us a favour by flying cheaply." Actually they are. Not intentionally of course, but are forced to because of competition. How many average working-class people could afford to travel to Bali if it cost several thousand dollars in economy? But your statement reveals I think the crux of your issue with airlines - you seem to think that they SHOULD be doing pax a favour......
IMHO the modern airline industry has evolved from many many years of difficulties to a point it caters to every taste. Anyone can choose to fly from A to B at the cheapest possible price, in economy, or pay for higher levels of comfort and service in a broad range of options from PE through to opulent F. LCC's are the pinnacle of the cheap-as-chips options. But as Dajop points out, some markets are not succesful with LCC's, so in those the airlines offer slightly better base products, but at a cost increase.
Last comment in this post, airlines suffer so much competition, and price pressure from pax, that they now resort to other areas to try to stay profitable. Hence the rise of frequent flyer programs. This is, in my opinion, a great illustration of just how hard it is to stay afloat, let alone make a profit, in running airline services.
If the reality was that providing better service, at the cost of higher prices, would win customers, then airlines would do that. Who decides these things? The consumer. In the thoroughly free market that the airline industry is that we travelers enjoy.