The new generation of commercial airplanes are so radically different from how we have flown for the past 20-plus years that stepping onto one can feel like flying for the first time.

The most obvious change is the thinness of the seats; the old-time bulk has been lightened and streamlined. But the differences continue to unfold. Lighting has been recessed into the ceiling and is often colored for a calming effect. (It was light blue as I boarded a recent American Airlines flight from Chicago to San Francisco.) Overhead bins have grown and now swing down from the ceiling, rather than simply opening forward into the aisle.

Some planes include a monitor in every seat back, featuring an entertainment lineup of books, movies, television shows and a touch-screen map to chart the flight's progress. Most essentially, these new airplanes can feature power outlets and USB ports at every seat (as that American flight did).

While there's plenty to like, there also is reason for consternation: namely, dwindling space and comfort. Most everything has become smaller, including seat width, seat pitch (the distance between the seats, which results in decreased legroom), tray tables, aisles and even the little pouch in the seat ahead. Where once we could store a water bottle, laptop and book ahead of us, we're now lucky to fit a couple of magazines.

Add it up, and we have entered a marked new world of airplane interiors.

"The industry is evolving faster than it ever has in the past, without a doubt," said Mary Kirby, founder of aviation news website Runway Girl Network.

"Airlines are tightening up the pitch in economy-class cabins and distracting people from that discomfort — or at least trying to distract — with the latest generation of entertainment systems and connectivity."

Trade-offs

There it is in the proverbial nutshell: the good (Wi-Fi! Touch screens! Power outlets!) and the bad (so very uncomfortable). My Chicago-San Francisco flight had even less legroom than it otherwise would because of metal boxes beneath every seat that an airline spokesman said were necessary to power the touch screens.

I might have preferred simply to be able to extend my legs.

But this new generation of planes is swiftly becoming the standard; American, for instance, said it is in the process of updating its fleet with 460 planes — "largest aircraft order in aviation history," I was told. That includes 100 new 737s (the plane on which I flew), where main cabin seats have an inch less of seat pitch than the previous generation.

Fern Fernandez, American's vice president of global marketing, painted the changes as net positives for the consumer but acknowledged that while the updated interiors are in response to consumer demand, they also boost revenue.

"Being able to generate additional revenue is obviously important to us; it's critical to us," Fernandez said.

The airlines are increasing revenue twofold with the new planes: They're fitting in more bodies, whether with more rows or more seats in a row, while also offering the miracle cure of extra legroom at a cost. American calls it Main Cabin Extra. United, Economy Plus. Delta, Economy Comfort.

All those programs amount to the same thing: the slightly comfier flying experience of yore, for a price.

"It's been headed in this direction for a long time," said Bob Mann, an aviation industry analyst.

Mann said that the changes can be considered good and bad for the consumer and that the two often overlap. For instance, while the new, roomier overhead bins are "a huge positive," more seats on airplanes mean that more overhead space is needed. It is, therefore, not quite extra space but necessary space.

And despite the touch screens and power outlets, physical space has become "not only uncomfortable but unusable."

"There are already seats in service before this latest generation with 30- or 31-inch pitch that I don't find usable for anything but a shuttle trip," Mann said. "A half-hour in that seat and my knees lose sensation."

Sensible from airlines' view

But maybe that's just clever business.

"There's a school of thought — and it's understandable — that says the basic economy experience is so uncomfortable that it forces increasing portions of people to seek a buy-up opportunity to something that represents a sufficient experience," Mann said.

Sure enough, when I expressed my semi-dissatisfaction to American about its new interiors via Twitter while still on that Chicago-San Francisco flight, the airline offered the following reply: "Josh, check out our Main Cabin Extra seats the next time you travel for additional legroom."