Herod's response is intolerant. We need but look at the world around us to discover the answer, at least on the surface. Tensions run high, on a continual basis, between the Jews and the Arabs. The Serbs fight the Bosnians in what is essentially a religious war. Rival tribes battle in Africa.
Mankind is always at odds with someone over something.
Maybe twenty children are killed. Herod's response is recorded in Scripture to demonstrate the importance of Jesus' birth - and to show the contrast between the forces of Light and Dark. The initial evangelistic prophecy and action finds this battle in full force. God curses Satan, and in that curse we find the basis of all else. Notice a couple of other important points from the story about the Magi.