The two forward positions are used for high gloss photos and image videos.
Yes Sir, no pilot is gonna depart a shorter "runway", when he can depart a much safer longer "runway"! the three most useless things in aviation! "runway behind you, altitude above you, and "airspeed" you don't have!"
famous but true old aviator saying, in other words always use all the runway, always maintain a "safety factor" and have plenty of altitude, and keep your speed up, when you get low and slow, and attempt to maneuver, the "stall, Spin"... more aircraft have likely been lost on the turn to final than any other scenario in aviation, with the possible exception of departure accidents..
Hence the wise Chines pilots are always gonna use the longest launch position, unless operational considerations dictate otherwise!