I have not played the game,
that said, what you said about weapons being retrieved from monsters, that is what I imagined ff13 to be when I first heard about it. That should add new dynamics to the battle system. I think as long as you do it well (which, in my opinion, ff13 didn't do well) you can call it FF. i have to admit, that what drew me in to the FF series, is decidedly missing from the later ones. My favourite is still 9, for the sheer fact of sidequests, and great abilities in battle. I persevered through to the end of the game and wanted to play it again.