>Game sells 5.5 million copies
>People call it a failure
It was the first RPG I played, there is nostalgia for longtime FF fans but that isn't the point of the game like revisionists say and isn't required to enjoy it.
VII and VIII built most of the western jrpg audience and IX appeared too childish for many to try. Many were disappointed with VIII because they couldn't figure out how to play it (many cases back then), the previous game's popularity affects sales of the current one.
Also, **the PS2 released a month before IX did in the US** and magazines were already hyping X.
Also, OP, Vivi does not "bring nihilism to the story," there's nothing nihilistic about Vivi.