I disagree. Male/female is used plenty with humans, but it tends to be used in a more clinical or 'objective' manner, such as in legal documents, autopsy reports, police suspect descriptions, things of that sort.

I think the use of, e.g., "Look at those four males over there", it has a bit of a connotation of separation of the personhood of the people involved. A man is a living, thinking being; he is worthy of dignity, and he has a soul. A 'male' can almost be called an 'it': it has a characterization of cold, scientific classification.