The issue is a practical one.  Most Catholics wouldn't know where to turn if they were told by a pastor that they didn't have grounds for annulments.   It is the same deal with children being refused the Sacraments because of their parents' "irregular" situations or couples being refused marriage because they are co-habitating.  I believe that this isn't allowed under Canon Law, but I doubt that many Catholics are going to know that they can challenge any denial.  They are just going to leave the Catholic Church.  One good, practical reform would be an easy process of appeal/ complaint for such situations.