(3) Repetition is not in and of itself bad in poetry. There are plenty of good poems that use it.
How is it used in this one? First they came for the X / And I did not speak out / Because I was not an X. For all of the variations of the English version of the poem (I'll get to the translation later) that is all the poem is for all of the verses but the last. You can see why people like it, it's very "accessible".