I'm sure it is a defense mechanism, just a more grown up version of that 2 year old thing when they say "no" to everything and fall apart if you say no to them.
I think all it takes to be able to accept the opinions of others is to notice these things going on in yourself and take your emotional responses as more information instead of the entire reality of the world.
Defense mechanisms and seeing social approval serve a deep evolutionary purpose so it never really goes away, but you can outgrow being governed by it.