On wide bodies
Aircraft performance improved, longer range flights become the rule. Keep Economy passengers seated and comfortable is essantial, but wjthout good sleep it becmes a torture.
Sleep is reducing long flights feeling. Arriving at destination with a good sleep passenger feels fit and able to start his professional or leisure day immidiatly instead of looking for a bed.
Mark up for LESAT sleep mode is a daily revenue. For instance with 50 € on two rotations a daly and 330 days a year increase the ancillary revenue per equipped seat with 33.000 € per year.
On single aisle aircraft.
Flight range increase on B737 MAX and A321 NEO or XLR are most cost effective as medium range aircraft to become long and extra long range ones. Lower operation costs point to point skip costly tranfer hubs. They become most competitive for transatlantic and transcontinental flights,
In Economy class, sleep and comfort improved with LSEAT are challenging even with 31 inch pitch and a decent sleep mode any passenger can afford.