I haven't seen many critics who are "merciless in their demands for photographic perfection" (except me). Most critics fixate on some compositional element, minor detail, or subjective feeling - which is natural, considering that most posts are completely without context.(posted 8648 days ago)Children's pictures are usually much like your album pics - personal snapshots, whose emotional value outweighs their artistic value. That being said, there are children's pictures which are quite powerful. (I can remember quite vividly a number that I have seen of Somali and Kosovar children - among others.)
The larger problem is that, when we take children's pictures, we usually take them out of their true environment and pose them in grotesque kitsch tableaux, using them to symbolize some sort of innocence which we think we once had (failing of course to remember the reality of childhood).
I think that it is that combination of the transference of our subconscious desires onto our children, along with our refusal to see their lives as they truly are (with all their fear, wonder, emotion, and naivete), that has created the vacuum that you note.
It goes without saying that our view of children needs to be emancipated from its fairytale prison, but the how is another problem. Perhaps the first step is to recapture your own childhood.