Final Fantasy XI came out over a decade ago, back when such things weren't regulated as well as they are at present. Furthermore, the presence of child NPC's is not the issue. It's the presence of playable children. The development team can strictly control what NPC's do and are exposed to. They cannot do that for player characters.

It's a little creepy that people keep ignoring that distinction in their efforts to paint the development team as 'lying' when they're quite clearly presenting a valid stance. It doesn't - or rather it shouldn't - take a genius to work out that there's a great many things present in the MSQ's and over-world that are inappropriate for a child character to be exposed to.