Would people still use the same demeaning language talking about European gypsies or immigrants? It is fundamentally an old, 19th-century throwback to the idea that that these people are somehow like our ancestors, or backward. It conveys that they are somehow not as intelligent as we are; that they haven't progressed as far as we have. It is fundamentally a colonial mentality.
Concerning the use of the expressions "stone age" and "primitive" in reference to some indigenous peoples, Journalists need to leave the Stone Age, The Independent, 23 January 2006