This is a very thought-provoking question, and it is one of those excellent statements that has arguments for either side. On the one hand, initially we could argue that eradicating mutations could have been necessary. Let us remember that this novel is set in a future dystopian world after some kind of nuclear holocaust that has destroyed civilisation as we know it. Given what we know about the way the human body reacts to radioactive materials and nuclear fallout, it could be argued that preserving the human form as it was became a matter of survival for the human race in the early days to ensure that sickness and other negative changes did not occur that could have wiped us out.
However, it is clear that in this novel, mutations have become much more than just a simple matter of ensuring the survival of the human race. They have become a religious obsession and a fixation for characters such as David's father, who believe that any deviation from the norm comes from the devil and therefore must be eradicated. Based on the Bible, they have decided that the human form as it is is the completed expression of God's will at its most perfect, and therefore that any deviation from that is wrong. Consider what the Sealand woman says about this:
The living form defies evolution at its peril; if it does not adapt, it will be broken. The idea of completed man is the supreme vanity: the finished image is sacrilegious myth.
This points us towards thinking that, although initially battling mutations would have been good and necessary for humanity, this has been taken too far and now is actually preventing humanity from adapting to the new world which they inhabit.