Rationale
The traditional anonymous peer review has been criticized for its lack of accountability, the possibility of abuse by reviewers or by those who manage the peer review process (that is, journal editors), its possible bias, and its inconsistency, alongside other flaws. Both processes are intended to subject scholarly publications to the scrutiny of others who are experts in the same field.
The evidence of the effect of open peer review upon the quality of reviews, the tone and the time spent on reviewing is mixed, although it does seem that under open peer review, more of those who are invited to review decline to do so.
Read more about this topic: Open Peer Review