On the so-called good poetry

On the so-called good poetry:
What is it that has happened to poetry and our judge of poetry since the beginning of this century? Why is it quite difficult to establish a common ground on which humanity can be able to reach a relatively mutual understanding concerning what good poetry means? At least based on the writings of poets of the past who leaves us their poems which, whatever their lasting worth, at least they quivered with vitality and prose that danced with such grace and gaiety on the threshold of the humanity.
What happened to poetry, that qualities like vitality and prose are hardly even considered now?
Weeks ago I held a discussion with students of English Language and Arts at Comboni College of Science and Technology; as part of the activities held weekly by Stallion English Language Society (SELS). I asked them to clarify what they mean by “good” in literary criticism context. Though most of them were within one generation, it seems impossible to them to agree on what is meant by a simple statement such as “this poem is good”. What indeed does it mean?!
Historically, to the Greeks in their best days, good poetry meant, above all, poetry that breed good men. The muses were the daughters of omniscience. The god of poetry was also the god of prophecy and healing, the voice that speak to the pity human to teach them how to fight, how to live, and most importantly, how to die. To them, the “great writing was the echo of a great soul”, a saying now seems so naive because it isn’t even agreed no more that literature has something to do with ethics, or poetry be anything as absurd as a sort of morals, set to music.
During the Renaissance, arrive also the critics. They declared the purposes of their historical noble mission. “To save literature from the ethical attacks off Plato, to subject it instead to the aesthetic rules of Aristotle”!
So historically, there was disagreement about what is meant by simply complicated question if I may say, as “what is good poetry? Or literary work in general”.
For the Renaissance it meant learned poetry; the poetry of scholars, and of wits. For the eighteen century it becomes the poetry of men-and-women of the world. For the Romantics, it means the poetry of generous rebels. Moreover, it is weird that up to now, after twenty three centuries, from the era of the father of Criticism, Aristotle, is there a single law of poetry or literature in general, a single principle for writing poetry, a single canon for criticising it, about which a congress of students of literature or critics would adopt as criteria? If the answer is no, so it will be hard to make the art of criticism sense and logical. For it is no longer agreed that poetry should be beautiful, noble, civilized, well constructed, musical, intelligent, or even intelligible.
Some people may argue that, the impossibility of finding a standard to what is meant by good poetry, is due to the fact that differences between human beings are extraordinary. Well, what about the fundamental likenesses, the experiences that human do possess and share? That thanks for it; after thousand years Homer, or Dante still fascinate remote barbarians like us.
Some criterion, in fact, some standard of judgments can and must be found in order to find justification for the continuum of criticism, values that humanity have admired for three thousand years whether in life or literature. qualities which has become second nature to most normal minds to find appealing, but which reason and experience also tell us we do well to like, qualities such as nobility, intensity, courage, generosity and pity.