As a rule, the answer is "yes". "nonessential opinionated material" should not be in the posts.
However, what one considers "nonessential opinionated material" is frequently subjective and in the eye of the be(er)holder.
Orthogonally, a very good suggested policy is to comment on an answer, pointing out what you consider offensive bits, and explain why you feel it should be edited for improvement. It's more neighborly than unilaterally making a major edit yourself, AND more importantly, lets the poster have a chance to explain why they may disagree. Beats getting into Wikipedia style edit/rollback wars :)
One caveat: if there's a clear evidence (via many comments/downvotes) that a specific piece of an answer is subjective opinion from many eyes, you may be better off editing it out yourself pre-emptively, lest an otherwise good post gets downvoted into oblivion. Then, post-edit, explain what and why you did in a comment (and for a new user, inform them of a rollback option)