Continuing the discussion from Voting/Auto-editor Request Thread:
So for FFI, FFII, FFIII there was only the very long arpeggios.
Then from FFIV onwards, the melody was added.
Was there other changes other than arrangements after those two versions?
I don’t remember hearing drastic changes requiring one work per game, but I mostly know FFIV, FFV, FFVI* and FFVII.
* The best ever. 
The main issue is that the composer, publisher and the video game music community at large consider them all to be separate works.
Can you be more specific?
From the ones I know (detailed in OP) and have been listening to for decades, they are just interpretations of the same PRELUDE work.
FINAL FANTASY PRELUDE / プレリュード as being the Press Start / New Game / Continue selection screen music (BGM) is meant to have a new recording for each game.
Same for the FINAL FANTASY MAIN THEME (heard in most ending titles).
When called FFXII Version for instance, we should understand it as a new recording, a new interpretation. Listen to it, it’s not a new work, it has same melody and chord progression.
That a new recording gets some new arrangements, I mean it’s what’s interesting with new recordings.
PRELUDE has those two versions, no doubt.
But the others. 
Please be more specific (with links, maybe?) where the composer, the publisher, the gamers consider PRELUDE and THEME are many different works.
Citation please. The composition is literally the same, the name/title is the same, the credited author is the same…
Here’s a source where someone in “the community” clearly does not consider the Prelude from the first 3 games to be different works (the most relevant section of the video is 0:42-3:23):
Last time this came up with the same composer:
https://musicbrainz.org/edit/70681138
https://musicbrainz.org/edit/70680477
https://musicbrainz.org/edit/70681103
Guidelines for the usage of “version of”:
https://musicbrainz.org/relationship/7440b539-19ab-4243-8c03-4f5942ca2218
This relationship should only be used when separate works are needed (e.g. when there are significant changes to the lyrics or music). In most cases, new versions of a work should simply be performances of the original work.
Still I agree that the addition of the melody (since FFIV) of course deserves a second version work. But after that, not sure they are more than recordings, based on the examples I have linked.
But I have not listened to all of them, so tell me if you spot something. 
For example, on Release “OPENING Tracks 1987-1996” by SQUARE ENIX MUSIC - MusicBrainz we can see the opening to the first 6 of the Final Fantasy games collected.
Yes, 6 recordings (of 2 works), not 6 works. 