agree that we can stop bashing subclasses in general.   The problem with numpy subclasses is that they were made without adherence to SOLID:  https://en.wikipedia.org/wiki/SOLID.  In particular the Liskov substitution principle:  https://en.wikipedia.org/wiki/Liskov_substitution_principle . 

did not properly apply them in creating np.matrix which clearly violates the substitution principle.