This question is a follow up to

As of 4.1 RC3, associated model data is still not created when using Ext.create("<Model>", ...) or new <Model>(...). The data has to be processed by a Reader for the association data to be created.

Is it be design, and if so what's the rational behind that? If I'm able to provide the relevant data to my model constructor, I expect the model constructor to create the associated model accordingly.