Hi there and welcome -
I think that being judgemental is an essential part of the witnesses' psyche. As they put themselves forward as the only true religion then the natural consequence of this is for their followers to believe that they are right. It's this deeply ingrained sense of 'being in the right' that develops into a habit and can be therefore difficult to break.
JWs are constantly bemoaning the lower standards of ' worldly people ' and rejoice smugly in their own superiority, although we all know that this is a complete joke. It's a hard habit to break, but as time goes on it gets easier.
FF