The key is in the “message.”
But, if this is the case, why aren’t other divine messengers represented with angelic wings? Shouldn’t this apply also to the Apostles and other prophets of the Old Testament? The answer, according to A Reader’s Guide to Orthodox Icons, lies in the Gospels themselves.
In the Gospels of both Luke (7:28) and Matthew (11:11), Christ explicitly says that “among those born of women there is no one greater than John.” A liturgical hymn sung on the feast of the Baptist’s nativity proclaims John is “the culmination and the crown of the prophets.” He is understood as holding a special place among the saints: he is a heavenly man, described as the “Angel of the Desert” (that is, the “messenger” in the wilderness).
The Baptist’s life in the desert, according to tradition, was “angelic” for two main reasons. One of them is quite self-evident: as he proclaimed the coming of the Messiah, he became a messenger of God, a “herald,” just like the angels. But also, the Baptist is the prototype of monastic life: he lived a life of prayer, abstinence and chastity, disregarding material needs, proclaiming the coming of the Messiah, becoming a herald of God like the angels. This has been often referred to as an “angelic” life, and that’s the reason the Baptist is the patron saint of hermits.