This article is from the Final-Fantasy and other Square Soft Games FAQ, by email@example.com (Nick Zitzmann) with numerous contributions by others.
According to an early 1999 interview in Next Generation magazine, Final
Fantasy creator Hironobu Sakaguchi said that the game was named the way
it was because when the game was being developed, it was his last effort
to make a worthwhile fantasy game. Sakaguchi was also involved in the
production of previous Square games, such as Highway Star (aka "Rad
Racer") and 3D World Runner, and wasn't happy with the way either one of
them turned out.