CTAS (Create Table As Select)and NOT NULL Constraints

Stumbled across YAOF (Yet Another Oracle Feature) today; When performing a CTAS (Create Table As Select) NOT NULL Constraints are usually created, for example:

CREATE TABLE ctas_test
  ( id   NUMBER NOT NULL
  , name VARCHAR2(30) NULL );

CREATE TABLE ctas_test_copy AS
  SELECT * FROM ctas_test;
  
SELECT table_name, column_name, nullable 
FROM   all_tab_columns 
WHERE  table_name LIKE 'CTAS_TEST%' 
ORDER BY table_name, column_name;

As you can see the Not Null Constraints have been successfully replicated to the CTAS_TEST_COPY table. However if I now execute:

CREATE TABLE ctas_test_minus AS
  SELECT * FROM ctas_test
  MINUS
  SELECT * FROM ctas_test;
  
SELECT table_name, column_name, nullable 
FROM   all_tab_columns 
WHERE  table_name LIKE 'CTAS_TEST%' 
ORDER BY table_name, column_name;

The Not Null Constraints are missing from the CTAS_TEST_MINUS table.