ATOs that are carrying out training for the commercial and instrument rating may well have that requirement. (They usually want, as a minimum, CPL holders with an IR, for obvious reasons) Other ATOs and certainly DTOs, why would they?
I've been carrying on as a CFI happily now, for more than six years, with just a Class 2. Class 1 became a waste of money for me. Only one of my instructors still bothers to keep his.