Apparently, Hironobu Sakaguchi was so impressed by EverQuest, he decided to apply the concept to Final Fantasy:
In early development there was debate over whether the game should be called “Final Fantasy Online”, as there was uncertainty surrounding if storytelling in an MMORPG could be of a standard expected from previous titles. However, once the core storyline was written and reviewed it was decided to be worthy of the main series, and the game became Final Fantasy XI.
Did Sakaguchi give his blessings to the project? Of course, he was “Executive Producer” of Final Fantasy XI. But that might not mean much.
For example, in 2012, Jay-Z was announced as executive producer for NBA 2K13. His role consisted of appearing in an introduction, picking songs for the game’s soundtrack and contributing to the design of its in-game menus “and other visual elements”.
Sakaguchi might not have been in control of all the decisions surrounding Final Fantasy XI’s “naming convention”. Also consider that after Final Fantasy: The Spirits Within
flopped bombed didn’t quite reach the numbers Square Enix expected.
A longtime proponent of bringing together the story-telling vehicle of film and the interactive elements of games, Sakaguchi debuted as film director with Final Fantasy: The Spirits Within, an animated motion picture based on the Final Fantasy series. The movie was the second-biggest animated box office bomb in cinema history, losing over $120 million dollars and leading to the closure of Square Pictures and reduced Square’s financial capital. Sakaguchi stepped down from his post as an executive vice president at Square. Square merged with their rival, Enix Co., Ltd., which led into the present day Square Enix in 2003. Sakaguchi resigned his position at Square.
Perhaps Square Enix renamed Final Fantasy Online for a sales boost? And without Sakaguchi in the executive vice president role, they could have done so.
So did Sakaguchi himself want MMOs to be apart of the mainline series?