Once we realize that the Luke who wrote the "Gospel of Luke" is the same one who travelled with Paul, it should be no surprise that one of his distinctive emphases is that the Good News is for both Jews and Gentiles. Over and over in this telling of Jesus's story, we hear that the gospel shall be "for all the people," even as early as the angels who addressed the Shepherds.
Luke, the Gentile who writes a Gospel, is eager to remind us that it is for everyone!