1) Have you MET Japanese culture? Are you NOT familiar with the incredible amount of Doujin and Hentai manga/art depicting sexual and lewd acts with children? Yoshi-P has literally advised and answered questions in some past live letters/interviews regarding adding kids for adventurers or warriors of light for the sake of being a child (in this case, as a playable race), would cause issues because of the demented and mentally screwed up people in the world who may RP and give FFXIV the bad rep because of it. Yoshi-P doesn't want that reputation. And I can understand and agree with that similar nature in mind. The NPC's are in this game, but have no real affiliation to you whatsoever other than "that one person who everyone knows, who helps people, and thus, you have a new job to help them!". That's it. Nothing more, nothing less. The problem is, people are ASKING for children and again, comes back to reputation if the issue pops up with RPing and that happening. Sadly, as most other enjoyable things in life, we can't simply have "nice things" because there's people who WOULD ABSOLUTELY RUIN IT FOR OTHERS. Even outside of this information, the problem still remains that as children owning them, similar to pets and minions, there are people who would intend to ruin it for the sake of ruining it for all. Because people are logically incompetent and/or stupid, in the sense.
2) Zhloe and Khloe work well because they're just there for the crafters and a side story and/or for gatherers. Sad story nontheless, but still there as is. When you're not doing that, other adventurers are doing the work to help them out. You don't even have to think about it. It's one and done on that issue. There's no RPing with the npc who thinks of you as just another person, except better than most of the other NPC's in lore.
Maybe it is content people want. Maybe in some games like Skyrim and the Sims, it's more acceptable. Maybe in some other MMO's it would be okay. Final Fantasy is not one of those game titles. Period.