Brooks Otis, in his Virgil: A Study In Civilized Poetry, devotes his second chapter to exploring the "epics" written after Homer, the Callimachan rejection of any sort of modern epic, and then the set-up in ancient Rome that would allow the Maecenas group (which included Horace and Vergil) to write polished, continuous epic once again. Otis notes several interesting things:
(a) Homer had written the Greek epic and it was the specific output of his culture and milieu. Callimachus and Theocritus argued that their contemporary relation to the subject matter of the Iliad and the Odyssey was such that a recreation of that was impossible. "It was not only the genius of Homer which made him unapproachable: it was also his age and his ideas." (Otis, Brooks. Virgil: A Study In Civilized Poetry. "The Obsolescence of Epic", pg. 6.)
(b) In positing that epic could no longer be written, Callimachus and Theocritus were not trying to subvert the path of poetry radically by killing or finishing off the epic form, saying "It's impossible to write epic any more. And, just in case it is possible, I'll give it a few more stabs." Otis says, "Unlike Euripides, [Callimachus and Theocritus] had no new, iconoclastic ideas, but at least they were willing to accept the results of his iconoclasm and to acknowledge the almost complete obsolescence of the heroic-mythical world view." (ibid., pg. 9)
(c) "The fact that long epics still continued to be written did not [for the Callimachan school] in the least alter this general situation." (ibid., pg. 16.)
(d) The definition of poetry, subsequent to Callimachus and the rise of "light" and lyric poetry, had been dominated by the Homeric subject matter to the degree that the Greeks hardly considered poetry not dealing with the heroics of men and the deeds of gods to be poetry at all. "This was [Homer's] mythical subject-matter—more exactly, his limitation of poetry's proper content to a cycle of heroic myths in which men were almost inextricably mingled with gods and other divinities.... Homer's influence and reputation had in effect fixed heroic myth as the proper subject of poetry." (ibid., pg. 6.)