The NCLEX is designed as a screening tool used to identify candidates that can demonstrate that their nursing ability is sufficient to be competent in practice. Providing more detailed feedback for candidates who fail is done in an attempt to help the candidate direct their remediation strategies. Providing feedback to people who do not need remediation serves no purpose and could be misused by candidates or employers in making employment decisions.
More information on the Candidate Performance Report (CPR) can be found on the NCLEX site.