I think it's true that they'd restrict rules so there are more "sinners" - however no children would actually be "raised" as handmaids.
When June's in the red centre, Aunt Lydia tells the women that it'll be easier for the generations who come after them, suggesting that some girls will be born and raised to be handmaidens, not just forced into it as punishment.
I tend to think that Gilead's leadership hadn't got around to thinking too far into the future, so it might simply be an inconsistency to be ironed out later. Or maybe, in twisted Gileadean logic, they've imagined a future time when some young women will want to become handmaids of their own volition. The public story being that the women see handmaiding as a noble calling. Eurghhh.