There is a puzzling dichotomy in twentieth century poetics. Let us call it the division between aesthetics and the anti-aesthetic. It manifests itself in the debate between art itself (on the one hand) and socio-political uses of art. We are all familiar with it, on both sides of the debate. Poetry has to do something important and socially useful to be justified; poetry that does not do this should be condemned. On the other side of the debate, there is an "art for art's sake" position that claims that doing this, sacrificing aesthetics, will ruin poetry.
Both sides of the debate are actually in complete agreement with each other, deploying the exact same dichotomy without questioning it. In other words, everyone agrees that making poetry or art politically useful ruins it, and that politically useful art will have to subscribe to anti-aesthetic principles. You can try to make it work, by saying that some people have managed to make poetry come out politically correct without ruining it, but within this conceptual frame we pretty much know that these will be seen as exceptions.
So the puzzle is that this dichotomy would have not been comprehensible 100 years earlier. If you asked Shelley about this, he would not have understood what you meant. Or Milton or Spenser. The terms were not yet in opposition; the debate was not framed in that way in the least.
So there had to be a moment in which the debate got framed like that. It had to be in the Victorian era, in the debate between moral earnestness and aestheticism, because I don't see it before that. Spenser would not have seen a dichotomy between expressing his particular point of view and writing good poetry.
Now we could see the separation of the aesthetic as such earlier, in the 18th century, but without all these implications in play. This separation of the aesthetic is the original sin, since it leads to dire consequences. In particular, it seem both to exalt the aesthetic and to diminish it as merely aesthetic. To say that the aesthetic was not distinguishable as such from other considerations is not to say that it did not exist, but rather that everything was aesthetic in the broader sense. In other words, there was a total ethos that encompassed the entire creative enterprise, but this entire enterprise remained a creative one: there could be no tension or dichotomy between writing a great epic like the Iliad and doing something else that would diminish the value of the work in order to achieve some other end.
When that total ethos is broken, then we can ask whether we can still appreciate poetry that tells us the opposite of what we believe. From the hermeneutic perspective, we get the problem of belief. The aesthetic now serves as a way of expressing enthusiasm for works that don't allow us to identify with ideologically. This is easy to see, since we don't have deploy aesthetics separately if we already like what the work is telling us. We can simply embrace the work enthusiastically, in its total ethos. There is no turning back at this point, because we realize that this embrace is going to be rare occurrence.