This is my understanding, anyway. The job of the reviewer of the NIH grant application is to discuss the merits and weaknesses for the audience of the Program Staff within the ICs. One is supposed to be helping them to make funding decisions with respect to the current pool of applications.
The job is not to help the applicant improve her chances the next time. Nor is it to help the application be more attractive for the PO/IC.
This is my understanding, anyway.
See ProfLikeSubstance's comment.