“Unless there is a good reason for its being there, do not inject opinion into a piece of writing. We all have opinions about almost everything, and the temptation to toss them in is great. To air one’s views gratuitously, however, is to imply that the demand for them is brisk, which may not be the case…”
William Strunk Jr. & E.B. White Elements of Style [I totally disagree; all writing is an attempt to persuade someone of a point of view.]