I don't think Final Fantasy games are made for children. Plenty of aspects of Final Fantasy games are very much in the 'adult content' region; even as far back as the original Final Fantasy there were 'dancers' (I mean strippers/prostitutes). Mature, or at least less fanciful fantasy storylines have been done before: Final Fantasy XII, Final Fantasy Tactics, Final Fantasy VI, probably smurfing all of them if I think hard enough. You look at the themes covered and tell me assassination, rape, torture, patricide, suicide, and genocide are just for kids.