I feel the need to report that, back in the lamb-white days days of USENET, critical reception did exist. Why, the X-Files had a whole separate newsgroup for it, because it was so unwieldy and abstruse. A fair proportion of the B5 moderated group ended up in in-depth discussions too: in both cases, more on the fact-checking and imagery-gathering and "wait, that makes no sense" side of criticism than on the social-issues side.

Some of the participants therein ended up Princesses as we know them now (and on LJ, though none are associated with Metafandom that I know of); and some I think were Scary Ponies testing out the waters (B5 was a particularly Pony-friendly fandom). Quite a few others would not today identify themselves with any flavor of fandom.

So it's not the critical reading itself that has developed as the Princesses have gone LJ; it's the spread of critical reading from one or two areas across the wide spectrum of Princess culture (and onto topics more weighty and political). Or anyway, the spectrum of LJ-based Princess culture.