Or why have the 787-10 when it does not fly as far as the 787-9? The old movie line comes to mind, "you complete me". A carpenter has more than one screwdriver type in its toolbox. A carpenter has more than one hammer too. The 787-10 is that special hammer or also called a "finishing" hammer. Most noted for pounding skinny little nails into wood molding when finishing a home. The 787-10 completes the family and is not a framing hammer for 16 penny nails. The 787-10 carries about 330 passengers as designed and it also flies 80% of the world's population connections with its dampened range of about 7,000 miles vs the 787-9's 9,000 miles, depending on passenger configurations and wind.
The 787-10 finishes the 787 families of aircraft for an airline's toolbox enticing passengers with competitive pricing. It's the finishing hammer making symmetry out of a home before the carpet is laid down and after the wallpaper goes on. Boeing has completed itself with the 787-10. Who would buy the 787-10?
The question was posed to its current customers and Emirates responded with an order for 40 787-10's, that's who! There was some magic in the numbers that have appealed to Singapore Airlines. A seven thousand mile circle was drawn around Singapore and "Viola" it was Singapore's core market. There were billions of people within Singapore's reach. The 787-10 could pack in people and move them where it wanted within its world. They could load a margin of the people on long range excursion to America or Europe on another Boeing 787-9 type going long. That "other" 787 was 95% like the 787-10 while making it a natural companion in the fleet. Singapore had already bought a slew of A-350-900 before the 787-10's concept arrived, but buying 49 787-10's was a remarkable tip of the hat towards Boeing's family plan. Its own airline offshoot, Scoot, bought the 787-8 and 787-9 for its fleet expansion and replacement in its budding aspirations. Emirates committing to 40 787-10 was a remarkable order as well, and a trend was established that the 787-10 completed the 787 concepts.
The synergy of it all, the 787-10 made the 787 family a stronger team than what its competition could offer, and it is beginning to take over the widebody market without a doubt. One pilot to another can fly all three with minimal training when transferring from one to another of the 787 types. That is Boeing's overarching plan of establishing a high bar of excellence defining the industry with its 787.