Most of the action on this is in something the article only barely mentions: safety. First of all there's the evacuation angle. Regulations require the ability

Most of the action on this is in something the article only barely mentions: safety. First of all there's the evacuation angle. Regulations require the ability to evacuate the plane within 90 seconds, using only half of the exits. And by "evacuate" they don't mean people lined up at the door waiting to get off -- they mean the order to evacuate is given, and then 90 seconds later there is nobody left inside the plane. There's a strong argument to be made that this is no longer physically possible with high-density seat configurations. The tests for this are already unrealistic (they involve people who are told in advance what's going to happen, who know they aren't in danger, who don't face any issues such as smoke to confuse them, and who have no particular attachment to each other or to any baggage in the cabin), and as those tests have remained static their detachment from reality has grown. The second issue is survivability in an economy-class seat. This diagram is instructive: https://img.thedailybeast.com/image/upload/d_placeholder_euli9k/dpr_2.0/c_limit,w_585/fl_lossy,q_auto/170912-irving-coach-embed3_khqwee https://img.thedailybeast.com/image/upload/d_placeholder_eul... That's used by airlines... for flight crew seats. It lays out an area to be kept free of obstructions, as anything in that area could cause devastating head or neck injuries in an accident (due to the seat's occupant being jerked suddenly and their head sweeping through that area). The diagram notes the area is 35 inches deep, but it's easy to miss an important point: the 35 inches is measured from the front of the seat cushion to the rear edge of any object in front of the seat. For passengers, airlines measure pitch from the rear edge of one seat to the rear edge of the next, meaning a 30-inch pitch (typical for US economy class) is not 5 inches (35 - 30) short of the safety margin, it's more like 8 or even 10 inches short depending on the depth of the seat cushions and frame. There are court cases going right now over whether the FAA is inappropriately ignoring safety concerns. A victory in court would, as a side effect, probably make flying more comfortable but also slightly more expensive.