In the staid, sober context of Medieval liturgical music, the odd, syncopated, "jazzy" effects of hocket would seem to have been out of place, to say the least. And there were, indeed, a great many complaints, throughout the period, from clerics who descried it as "flippant, uncouth" and even "depraved." Nevertheless, the practice was popular and the works of a great many of the most notable 13th and 14th century composers were replete with hockets and hocket-ridden passages.
In the words of William Dalglish, the hocket
was not, as some modern writers have intimated, a technique of purely subordinate import. Indeed, in certain music of the late ars antiqua, its use bespeaks a degree of ingenuity and sophistication rivaled only by the isorhythmic motet in its most advanced development. To misunderstand the hocket is to overlook much of significance concerning the craft of composition and the art of improvisation in the music of medieval Europe ["The Hocket in Medieval Polyphony," The Musical Quarterly, Vol. 55, No. 3. (Jul., 1969), p. 344].While the hocket has often been treated in the context of "learned" (two syllables) composition, as an exploration of certain rhythmic possibilities opened by new developments in notation, its origin, according to Dalglish, was not due to the efforts of trained composers, but more likely stemmed from an older tradition of "improvisation":
[M]y intention is to demonstrate something of the probable importance of improvisation in the musical life of the Middle Ages by establishing that hockets were first extemporized by singers and only later written down by composers ["The Origin of Hocket," Journal of the American Musicological Society, vol. 31, no. 1, spring 1978].
Dalglish doesn't make clear exactly what he means by "improvisation," nor does he make much of an effort to explain who the "singers" were or why they might be interested in improvising hocketed passages. The whole question of hocket, its origins and the reason for its existence would seem to be a complete and total mystery, unless . . .