There is probably nothing wrong with art for art's sake if we take the phrase seriously, and not take it to mean the kind of poetry written in England forty years ago.
How does one happen to write a poem: where does it come from? That is the question asked by the psychologists or the geneticists of poetry.
I am not ridiculing verbal mechanisms, dreams, or repressions as origins of poetry; all three of them and more besides may have a great deal to do with it.
Serious poetry deals with the fundamental conflicts that cannot be logically resolved: we can state the conflicts rationally, but reason does not relieve us of them.