(1) OK it's a "poem", everyone knows it, everyone currently is wallowing in it, it's bad. Why the scare quotes around "poem"? Because it was not written to be or really intended to be a poem.
I should write at the outset that although Niemöller was basically a Nazi, I firmly believe in a separation of artist from art. It's possible for a bad person to make good art or a good person to make bad art. Criticism of who he was is not why it's bad art.