I think the problem with kidfic is that it can quickly go the way of the Mary Sue; you know, the child is so precocious and intelligent and very Emperor's-New-Clothes that it overwhelms the actual characters in the actual story, which, in some cases (but NONE of the authors recommended here, I hasten to add), is not all that bad a thing, because you can't even recognize the fandom from the writing.

Anyway, kidfic done well is excellent; it's also realistic. (I mean, seriously: NO ONE EVER gets pregnant? Or feels the biological clock? Or anything?) Kidfic done badly is painful.

Thus spake the prophet. Heh.