It seems to me that to write poetry you have to have an opinion about the things you perceive. You have to have a strong opinion, which is something people don't always like. But it is not necessary that your opinions are correct. However, what you write has to have an intellectual or emotional force, so that it appears at least, to be true to you. These opinions don't have to be right or wrong, but affirmative of their subject and the poems apparent meaning. It is better if things are true, but you are never going to convince everyone.
Without either intellectual or emotional force, preferably both, there is minimal hope of convincing a reader of what you say. In fact, you have to be opinionated, a word that is much used these days as a term of disapproval, or, more often than not by someone who doesn't agree with what someone else says but has no better answer than to call them opinionated. Its a sign of failure to call people opinionated.
My religious education teacher at school called me opinionated because I wouldn't agree with her opinion about religion, but she would not have considered that the religion she espoused, which was then enforced in the curriculum by the 1944 education act, was acting in an opinionated way by forcing their opinion on everyone else (completely without the benefit of evidence), whether or not they agreed to this indoctrination. I was quite happy to be called opinionated in this circumstance.
The other word people use in a disapproving sense is judgemental, which according to the Oxford Concise means 1 of or concerning the use of judgement. 2 having an excessively critical point of view. Neither of these statements seem particularly objectionable to me, as to the second of them, there more often than not seems to be a lack of critical thinking rather than an excess of it. I think I would like to add judgemental to the attributes required when writing poetry. Without making a judgement, or having an opinion of some kind, poetry would seem pretty insipid to me.