I had initially written a longer comment saying "remove this check when someone complains for a good reason" :-)

AppConfig is a at the same time a core class and a very simple class — it has a handful of attributes, one method and one class method. I find it unlikely that someone will have a strong requirement _not_ to inherit from AppConfig. On the other hand, the error messages if you put something stupid in INSTALLED_APPS can be less than helpful, especially if that something happens to have a "name" attribute.