(1) I guess I wanted MetroMind to be what in my fake Latin I call the "mater municipas" -- in other words, mother to the whole city, not just to a particular creation. Also, if Scraper was something she built, things get a lot more complicated with respect to their relationship (is she "favoring" her offspring, is it outrageous that she puts him in the line of danger, why hasn't she upgraded his intelligence, etc.). He couldn't be a Factorbuilt, though, because that created divided loyalty issues, too. [EDIT: Also, one thing I forgot, was that there was some significance to MetroMind not having actually "built" anything. Aside from soldiers, almost all the sapient bots you meet have built something -- Leopold -> EFL; O&C -> Rex; etc. The most obvious non-builders are Clarity (who is almost necessarily a "virginal" ice-queen), Crispin (whose virginal nature is revealed through his constant skirt-chasing), the soldiers (187, Primer, ELF, and Goliath), and MetroMind.]
(2) The suggestion is that each version reached the same epiphany that Horatio did, somehow, and locked the memories again because they couldn't cope. Or that it was an iterative / evolutionary process to move Horatio away from still being a destroyer ("wroth confusion") and into being a builder. It also helped introduce the version concept early in the game, allowing us to riff on it with Leopold and MetroMind herself. Finally, in an early design, the ending was going to be Horatio asking (a la the Matrix) Metromind to relock his memories (or relocking them himself) so he could go back to worshiping humans and tinkering in the desert, with the implication that the cycle would eventually start again.