In Aldous Huxley's Brave New World, the men speak of Lenina and other women as "pneumatic." Since there is no attraction of one person for another that is other than superficial and physical, this term is the highest compliment. The smooth skin and "cushy" feel compose sensuality for the women of the New World and little else makes them attractive to men.
Nowadays in our youth-oriented and sensually-geared culture, appearances have taken on significant meaning. So, in order to be judged as adequate as the woman in Brave New World are, women have cosmetic surgery. Likewise, since "perception is reality" for all, men seek to remain young-looking. As in the New World, when people begin to look old, younger people give them little or no credibility and, in essence, throw them away just as the aged in the New World are terminated. The aged, like Linda, are repulsive to the children at the hospital, and they ignore her and the others who are dying.
Although the people in the World State do not (that we know of) have plastic surgery or implants, they do continue to look young pretty much all their lives. The reason for this is that the State wants to take away real human emotions and have people just be superficially happy all of the time.
In this society, they rely on people being "happy" all of the time. They give them soma, they let them have the strong emotions surrogates, things like that to make sure that they do not truly experience emotions of their own. They need to do that because true emotions would make people into individuals and individualism has no place in their society. They want everyone to be the same so that they will be content.
If they let people age, people might stop being superficially happy. They might really feel themselves aging and changing. This would make them be more aware of themselves and their individuality. That would go against what the society wants.