Lorraine: I am definitely no expert. but I think the reason base cabinets have the back inset so far is to allow for trimming the sides to match any irregularities in the wall/baseboards (wall not flat or out of plumb), and also to allow running things like icemaker water lines, etc. behind the back during installation to keep them out of the cabinet space. Hopefully one of the pros will chime in here.:-?
Go
Go