Haha, I was waiting for someone to mention Fire2-3. Again, you are happy for that to change, but not other bits. There are far more dramatic changes one can make than a victory fanfare and that's why I don't get the big deal. I can understand people being upset about poor gameplay, poor characters, poor story, etc. But when people say "it's a different victory fanfare and this makes it no longer an FF" then my mind gets thrown a bit.
I still think it's predominantly do to with Nobuo not doing this one. I don't know for certain who has the tune copyright but it could well be that either the old or the new composer made a request for it to be different so that they can say "this is my work, nobody else does it as it's something I feel is tied to myself rather than the FF series". I'm sure they did think it over but there is more than one party to consider and I imagine that when the new composer was finally told he can have the entire game to himself, he would have been pretty annoyed if he was told that all the music that isn't going to be talked over is not allowed to be his own work. The lead composer should always be the one who created the "lead music" - I'm talking more theme music and intro music here than fanfare, but I imagine fanfare could be seen in a similar way.