[Someone1234]

But the airline is also using less fuel. They're now transporting 6 less passengers and any luggage (even carry-on).

It also reduces stress on boarding, reduces some fees the airline pays, and while staffing cost per passenger increases, the airline's profit per passenger increases in kind.

Plus a lot of airlines don't even offer an Economy comfort class, and even fewer do on all of their aircraft.

The biggest likely impediment to this isn't the economics or business, it is that reseller sites only focus on price. They won't even tell you what the seat pitch/width is, they'll just tell you that seat A is $135 and seat B is $150.

[reubenswartz]

This is why I miss American Airlines "more room throughout coach" that they had ~20 years ago (am I really writing that?). You'd know that you'd get an almost comfortable amount of legroom. If it was ~$20ish more for a long flight, totally worth it, especially if you want to take your laptop out.

Of course, the real thing is that customers are voting with their wallets, and they generally prefer as cheap as possible.