If you accede to this request the whole peer-review process goes down the tubes. Reviewers will be able to request the earth from authors. If we all started doing this the number of reviews we could do would dramatically reduce. I currently do about 20-30 reviews a year. If I began asking for this sort of information from journals (AMS, AGU, RMS etc) I would be laughed out of court. I guess it would stop the papers to review coming. The whole system would grind to a halt. I've never requested data/codes to do a review and I don't think others should either. I do many of my reviews on travel. I have a feel for whether something is wrong - call it intuition. If analyses don't seem right, look right or feel right, I say so. Some of my reviews for CC could be called into question!