Well, I sort of agree with you there to a limited extent. But I'm getting the impression that you're trying to make every subjective opinion of equal value. You can then justify just about anything. Good becomes bad, pornography becomes fine art and the works of Shakespeare are no better than pulp fiction, depending on one's subjective opinion. Maybe you're right.
I think a better way of looking at this, is to say that we all have a certain expectation of the performance of a product, an expectation based upon reading reviews, word of mouth opinions and personal experience with other similar products. When those expectations are exceeded, we give the product top marks. When the expectations are merely met, the product might still be considered good and recommended. If the product falls below our expectations then we tend to give it the thumbs down. But you're right, if that's what you're saying, that peoples' expectations differ widely. Michael's expectations of camera performance is very high. There might well be quite a few people who already have a few Nikon lenses, who will buy the 14n, perhaps as their first digital camera, and will be thrilled to bits with its performance.