Every FF game has had fighting with swords and magic.
The culture is always thematically that of a world that's less industrialized, less infrastructure but with technology that progressed differently, either with the use of magic, fictional animals or simply advancing old technology along further.
Thematically it's been about saving the world.
Moogles, Chocobo, Airships, Summons, Red Mages, Boats, ext... not in every game, but they all have some of that.
The movie felt completely disjointed from any "Final Fantasy" type experience, and with the expectation of that, it led to a disappointment.
I believe the idea that FF fans would hate the movie more because of the FF name, that's true. Myself, I finished the movie baffled, not because the movie was bad in its own right (it wasn't bad... just not good...), it gave me expectations that it didn't follow through with.
Like a James Bond movie that's a romantic comedy. Maybe it would be a movie I'd have liked...but going in for James Bond, I'm gonna be pissed.
As for Advent Children... my biggest problem with it is that it establishes the ending. I felt that the ending was left in the air, with a strong hinting that the lifestream had eliminated the humans. Instead they bring it back, and for something's that's entirely pointless... I dunno.
I mean... it's still cool and all. It's like watching most anime. There's no plot that's worth shit, but it's cool fighting. It's like a big fantasy.
In general, the big problem with games to movie translations is that nobody puts any real effort into them, and that the medium translates badly.
I mean... a Metal Gear Solid movie COULD work, but in reality it would need to be 5 movies to translate a Metal Gear Solid experience. Same goes for a Final Fantasy movie... you can't make FF7 or FF10 into a 2-3 hour movie. Every game would require a 3 movie Lord of the Rings treatment to be the FF quality we'd expect as fans.
On top of that, the plot only makes sense in the contexts of the games. The relative strength of the characters change greatly as the game moves on, and such a leap wouldn't be possible in a movie setting. The characters hit 1000 times harder and are 1000 times tougher by the end of the game, and that means they had ordinary strength and went on to fighting giant robots with their bare hands and fighting people able to blow up cities. Character's relative strength, what level the plot expects you to be... effects how things play out in the story.
I do think Ratchet and Clank could be a decent Pixar movie, though it wouldn't be a Pixar quality story as it's not deep enough thematically.
Suikoden would be a good 5 part 2 hour each miniseries. Same goes to Tales of the Abyss.
Ninja Gaiden would make an exciting 2 hour blood bath with no plot.
I have to play more, but Rogue Galaxy might be a good movie if they just took the idea and did it kind of like Firefly.