Uh... the comment Cottle made was that he was amazed they *didn't* fix the plumbing. Which is to say, birth is nasty, brutish and long. And if an engineer were to reengineer the system, why make it just as nasty and brutish?
It's funny that two of the episodes you claim treated their issues well - "Black Market" and "The Woman King" - were actually among the most reviled episodes of the series. The most heard complaints about these two episodes? They weren't long enough to treat the issues they took on, or they went too far explicating morality to the viewer instead of allowing him/her to decide for himself.