It's by design. Airlines, like most industries these days have decided that it's no longer "Profitable" to serve regular folks, so they are pursuing the "Whale" strategy of re-orienting their entire service offering to exclusively cater to the 20% of their customers that drive 80% of their profits.

The experience of flying first class is better than it's ever been, and all that extra comfort, convenience and luxury has come 100% at the expense of the experience of the unwashed masses flying "Economy" class. First class gets lie flat beds, priority boarding, lobster thermidor and hot towels, while economy seats keep shrinking, boarding times get longer, checked baggage that used to be free costs $100, and a child-sized bag of peanuts costs $5.

The reason airline travel sucks so much these days is because it's supposed to. If you're flying economy class, the airlines literally see you as a burden, rather than a valued customer, and are doing everything in their power to make your experience as awful as possible, while squeezing every last penny out of you in the process.