In my opinion, this has to do with what Homer (assuming he actually existed) is trying to show in the story of Odysseus and the Cyclopes. Scholars of the epic say that he is trying to say something about Greek values. He is trying to show that unity among Greeks is important, that good, civilized institutions are necessary, and that the related quality of hospitality is vital as well.
The way that Polyphemus acts shows that he and the cyclopes reject these values. They are fiercely individualistic (the rest of them don't even help Polyphemus), they lack any sort of government, and in addition to that they do not honor their guests. Homer is using the cyclopes as an example of what not to do.
This is why the description of the cyclopes focuses so much on their lack of civilization -- he is portraying them as barbarians. Here's a quote that shows this focus:
“We sailed hence, always in much distress, till we came to the land of the lawless and inhuman Cyclopes. Now the Cyclopes neither plant nor plough, but trust in providence, and live on such wheat, barley, and grapes as grow wild without any kind of tillage, and their wild grapes yield them wine as the sun and the rain may grow them. They have no laws nor assemblies of the people, but live in caves on the tops of high mountains; each is lord and master in his family, and they take no account of their neighbors.