I think it is the default behavior for a good reason: the generators are meant to be used in context of an application. You should consider your addon/
folder being sort of a lib
directory, where you can use any file/folder structure that fits the best to your addon. The app/
folder, however, is meant to contain the re-exported modules, so they'll become available on the host app's container automatically.
Browse around a few well-written addons to find out how most people do this, a good example is the ember-radio-button
Notice that an abstact class like radio-button-base
is useless by itself, and, therefore, unnecessary to reside on the container, but an addon user would want to import and extend it for his own purposes, which he can do by writing import RadioButtonBase from 'ember-radio-button/components/radio-button-base';