Utopia is just something too good to be true. In the pursuit of it lies the most intolerable thing, deprivation of freedom and choice, and it leads to the worst ending.
He is to be trained to become the "Receiver of Memory." You see, in the Utopian society Lowry has created for us, the people don't want to be burdened with memories. However, they also don't want to make decisions or changes which, in the past, have led to disaster so they have assigned one person to keep all the memories of history.