Starting on Confluence 5.3, Confluence has the feature to Request and grant access to view a restricted page. (documentation)

The email request will be sent to either the last user (with appropriate permissions) to edit the page, the page creator or a space admin. (in that order)

It would be beneficial for space administration if this can configured in space level by the Space Admin. Therefore, the person who is responsible to approve/reject the access request will be fixed without any change.