Why are there so few video game endings we actually remember and talk about positively?
In an age where the majority of triple-A video games are designed to be played for literal years at a time - facilitating DLC and microtransactions, before a sequel resets everything all over again - the very purpose of an ending is forever changing.
Do you tie off all your potential story threads, running the risk of a satisfied consumer base not coming back? Maybe go with a cliffhanger, as whilst you might not have secured funding for a sequel, a surge of fan interaction could make that a reality somewhere down the line.
There's also the fact that developing a video game is incredibly hard. Budgets run out, key staff members leave or can have any number of emergency commitments.
Any large-scale title has a team-size reaching closer to 100 individuals, and the likes of Assassin's Creed or Red Dead Redemption 2 have that number doubled, tripled or more so.
All of this folds back into a game's design, and the challenge of executing on an initial vision becomes substantially more hard.
-- Spoilers within --