It's part of being open-minded. There are traditional, conventional views that the majority have taken in the past because they are sensible and practical. But, you see, when you take some odd-ball position that corrupts society you get scorned for being corrupt, or a radical, or a menace. The way to deal with the cognitive dissonance of decaying the moral fabric of society is to call yourself "open minded". You're not corrupt, you're not deluded, you're not embellishing in narcissism --you're open minded toward different beliefs. That makes you more enlightened, more thoughtful, more tolerant. Of course, we see that being open minded does not forbid you from condemning others beliefs. In fact, open minded people are quite ruthless and bigoted about their quest for a more gentle, tolerant world. And, if you hold different beliefs from them, particularly ones that are more in line with what is conventional, the cause and justification could not possibly be that you reached a different conclusion via a different line of reasoning --ironically, the same justification they had for being moral deviants; you're evil. Pure evil, and full of hatred, menace, bigotry and all things rotten and unholy.
Some people honestly think that their opinion is the only conclusion a reasonable person could possibly come to.