Why should I upload objects as reduce redundancy storage class on s3?

You can assign S3 object(s) as a REDUCED REDUNDANCY STORAGE while uploading file(s) and folder to s3.
RRS is a new storage class for objects within Amazon S3. It enables customers to reduce their costs by storing objects at lower levels of redundancy than standard storage. We recommend you to store non-critical, temporary and easy to reproducible data with REDUCED REDUNDANCY STORAGE.