Just to throw in my few cents here, I don't think II or III were made for children no matter how many people claim that.

I think II mainly pandered to teens (what "kid" would sit through the Anakin/Padme scenes, PLEASE), and III attempted to be a dark drama for all ages, probably the older ones (and it was, just with lots and lots of weak points and failures).

The darkness in the OT I can take as fitting into the "for children" concept, as it was basically a magical, escapist fairytale where the hero had to step into the "dragon's lair" a couple times.

The PT, especially the latter two movies, however is chock-full of political allegories and attempts to be some kind of Shakespearean tragedy.