Predicated upon a controlled environment, the utopia of the New World functions primarily because of eugenics in which a certain number of Alphas and Betas are generated to lead and perform more complex tasks while the Deltas and Epsilons are produced in greater numbers for the menial tasks. Without these controlled numbers of certain castes, there would be an overpopulation, perhaps, of the higher-functioning people.  If this overpopulation were to occur, there could easily be civil unrest leading to a revolt much like the Cyprus experiment to which Mustapha Mond alludes in Chapter 16 when he talks with John the Savage.Mond explains, “It would upset the whole social order if men started doing things on their own.”

So, if there were no Hatchery, babies would be born the natural way without the scientific control over their genetics as in the New World manner.  Also, people would have to experience the emotional involvement of procreating and becoming parents which would lead to personal attachments; such attachments, of course, are anathema to the working of the New World in which "everyone belongs to everyone."  It is the depersonalization of the sexual act and other personal encounters that keep people more controllable as they become dehumanized in their activities and more sheep-like and, therefore, content in their servitude. And, most of all, it is the control of people's intelligence level in the birth rooms and the control of thoughts as in the sleep conditioning introduced in infancy that effects these programmed people of the New World who act, for the most part, as the World Controllers desire.  On the other hand, without the Hatchery, people would yet be human and experience the emotions of the heart and the pain and energy of the body and mind if there were no hatcheries.