Just, Why?

I'm currently debugging a procedure of the form illustrated below, lovingly recreated using the ubiquitous scott.emp table. I'm also taking suggestions on what might've been going through the head of the person who wrote it.

RENAME emp TO emp_table
/
CREATE OR REPLACE VIEW emp
AS
   SELECT *
     FROM emp_table
/
CREATE OR REPLACE TRIGGER mod_emp
   INSTEAD OF UPDATE
   ON emp
   FOR EACH ROW
DECLARE
   new_emp                       emp_table%ROWTYPE;
   old_emp                       emp_table%ROWTYPE;
BEGIN
   new_emp.empno       := :NEW.empno;
   new_emp.ename       := :NEW.ename;
   new_emp.job         := :NEW.job;
   new_emp.mgr         := :NEW.mgr;
   new_emp.hiredate    := :NEW.hiredate;
   new_emp.sal         := :NEW.sal;
   new_emp.comm        := :NEW.comm;
   new_emp.deptno      := :NEW.deptno;
   old_emp.empno       := :OLD.empno;
   old_emp.ename       := :OLD.ename;
   old_emp.job         := :OLD.job;
   old_emp.mgr         := :OLD.mgr;
   old_emp.hiredate    := :OLD.hiredate;
   old_emp.sal         := :OLD.sal;
   old_emp.comm        := :OLD.comm;
   old_emp.deptno      := :OLD.deptno;
   update_emp (old_emp, new_emp);
END;
/

CREATE OR REPLACE PROCEDURE update_emp (
   old_emp                             emp_table%ROWTYPE
  ,new_emp                             emp_table%ROWTYPE
)
IS
BEGIN
   IF old_emp.empno != new_emp.empno
   THEN
      RETURN;   --can't update primary key attribute
   END IF;

   IF     old_emp.empno IS NOT NULL
      AND new_emp.empno IS NULL
   THEN
      DELETE FROM emp_table
            WHERE empno = old_emp.empno;

      RETURN;
   END IF;

   IF    (    old_emp.ename IS NULL
          AND new_emp.ename IS NOT NULL)
      OR (    old_emp.ename IS NOT NULL
          AND new_emp.ename != old_emp.ename)
   THEN
      UPDATE emp_table
         SET ename = new_emp.ename
       WHERE empno = old_emp.empno;
   END IF;
   -- ..
   -- ..
   -- ..
   IF    (    old_emp.deptno IS NULL
          AND new_emp.deptno IS NOT NULL)
      OR (    old_emp.deptno IS NOT NULL
          AND new_emp.deptno != old_emp.deptno)
   THEN
      UPDATE emp_table
         SET deptno = new_emp.deptno
       WHERE empno = old_emp.empno;
   END IF;
END;
/