Soren Kierkegaard said “Once you label me, you negate me”, and I believe this to be true for poetry as well. A good poem (and I’m well aware that there are many bad ones out there, I’ve written plenty myself) does not have one single, linear and easily explained meaning. For a poet to say, “this line means x” precludes any authorship of meaning for the reader and also assumes that the reader is incapable of fathoming meaning from words him/herself. This may be fine for readers who come wanting a poem. It’s insufficient for those who want poetry.
Poetry should not provide answers, but questions. Poets do not have answers. Poets are not judge or jury, but plaintiffs begging for a case to be heard. For a writer to assume that he/she is more enlightened than the reader is arrogant and – for the most part – a little bit stupid.
As a writer of poems, I may have intent when those thoughts roll off my pen – obviously I am thinking something. Once it’s written, though, my authorship is done. Each time I revisit the poem it’s as a reader. The best poems I’ve ever read give me an opportunity to focus on a different thought each time; the text becomes fluid the moment it engages with the reader’s mind.
However, it’s clearly not enough for a poet to write something obscure and esoteric, then say to the reader “well, you figure it out, that’s your job”. There should be a balance – and there has to be a key, something to allow the reader to unlock at least the first part of the meaning (or a meaning), even if it’s not leading to an actual thought process but rather to a given mood or ethos.
Finally, I believe that poetry is about enjoyment before all else. If you don’t know what it means, but you like the way it sounds or it reaches you in some way – does it really matter?