One reason that I use Brave New World at times when teaching political science classes is that the book shows the way in which totalitarian government treat people as commodities. I also use when I talk about Plato's ideas about a perfect society -- the book shows us what the dangers are of trying to achieve a perfect society through government actions.
In this book, people are treated only as machines, really. This is most especially true of the lower castes. The lower castes, especially, are mass produced so as to be interchageable pieces of an efficient machine. They are not meant to be individuals in any way. In fact, all individuality is taken out of them both by the physical process of creating the and by the conditioning that is done to them once they are born. We see people being taught to all be the same and to all have the same attitudes.
When the World State does this, it treats people as commodities -- as interchangeable things that have no individual purpose or value.