There was a 1.5 extension that did the same thing, that I have long missed. I was just working up the energy to write such a thing myself. It works exactly as promised.
One *very* small quibble that no one else will ever notice: If I have Error Reporting set to Maximum (under Server Settings in the admin Global Config), you can see a warning that should probably be fixed:
Strict Standards: Only variables should be assigned by reference in /htdocs/administrator/modules/mod_missingmetacheck/mod_missingmetacheck.php on line 15.
This does not appear in default Joomla settings. I further note that the current J2.5 has at least one similar error. :-)