People don't like to be criticized but to criticize. They often feel offended when someone criticizes them. Criticism, actually, is the best and free guardian for us. Nobody is perfect. So, everybody needs to get criticism to make him closer to perfection. People often say that they need 'constructive' criticism not 'destructive' one.
Well, I think every criticism is constructive depending on how we react to it. Perhaps, some people criticize others with certain motives: to destroy, to underestimate or to dishonor. No matter what the motives are, as long as we react positively to a criticism, it is constructive.