At the cost of fliers’ comfort, standing-room would enable the airline to sell customers cheaper tickets and pack in 40% more passengers per plane. Because everyone knows what airlines really need: bigger profits and more people inside every plane. Though thankfully, it'll be a while before airplanes turn into subway cars.
“We need many other conditions to make it work,” a Spring Airlines spokesperson told China National Radio. “Like working together with airplane manufacturers, getting the approval from the authorities and having the consumers accept the idea.”
And as Mashable notes, other low-cost airlines like Ryanair have proposed standing-room cabins, though they've yet to actually implement the change due to safety concerns. But standing-room only planes appear inevitable, because people are dumb enough to tolerate any debasement, so long as it's cheaper.