VIII has a lot issues which probably contributed to the lower sales of IX.
After VI and VII being master pieces the hype around VIII was huge... Unfortunately VIII ended up far from the quality of VI and VII.
Many thing hurting sales of Final Fantasy IX.
First thing is the Art Direction "Cartoon", people hating the chibi effect and thinking
"this is a FF for Kids" after FF8. Yet, this is the "natural" choice with FF7 semi-cartoon/chibi/anime.
Then, Square annoucing FF9 on Square Millenium in 2000, with FF10 and FF11... (Yes, at this GOLD era, Squaresoft announcing 3 fking mainline Final Fantasy).
Everyone looking the "
Next-Gen Final Fantasy" aka FF10 and FF11 Online for PS2 instead FF9 wich it's just "
another FF PS1".
Finally, the game was release on the big marketing launch of the PlayStation 2, the war with Dreamcast/PS2 and some "solid" JRPG at the same period. (Pokémon Gold/Silver when the world was on Pokémania, Dragon Quest VII on PS1 in Japan wich is VERY big in this country). Even at the end of the PS1 Era, another titles JRPG of Squaresoft sales poorly because of this and releasing at the same time of FF9. (Vagrant Story, Thread of Fate).
Sony was busy with their first party games but especially with the PlayStation 2. So they didn't distribute Final Fantasy 9 (but did for FF10) in PAL territories. While they had done for FF7 and FF8.
To top it all off, Squaresoft released some Screenshots of Final Fantasy X on PlayStation 2 when FF9 was even not released (they do the same thing with FF12 and FF13). And the PS1 emulation coming quite quickly
FFVII & VIII are in a class of their own, IX was something Square put out for investors while work was being done on X.
By Sakaguchi's own admission, FF9 cost $40 million, while FF10 cost around $35 million. So no, FF9 is not "
a small game for investors" (Which investors go to fund $40 millions a JRPG on PS1 in 1999-2000?).
Knowing that FF11 must have also cost more since we are talking about Squaresoft's first MMO.
Finally, FF9 was directed by Hiroyuki Ito, the co-director of FF6 (and game designer of FFTactics / FF4), it's not "
a small name with a small team".