The dissenting opinions can be used by the judge as a way to make sure they do not agree with the majority.
Hon. Ruth Bader Ginsburg wrote a lecture about the role of dissident opinions and on her lecture she points many reasons for recording dissident opinions, the first one is that a dissident opinion might be a good factor to make the opinion of the majority more refined and clarified.
Another reason to record a dissident opinion is to let it to posteriority, because sometimes - and we can see this many times in the US Supreme Court History - the opinion of the majority might be overruled in the future and the dissident opinion might become the majority, she calls this “appealing to the intelligence of a future day”.
