There is an error in this bug report. The initialize function is indeed called on sub-views. However, it seems that if an initialize function is provided in the sub-view configuration, the initialize function for the parent class is not called by default.
You can only override methods when using Ext.define creating your own subclass like you are doing in the Shopeel.view.PeelListNavViewContainer component. Where you trying to use the initialize event and not as a method override?
I originally had the NavigationView as a top-level class with an initialize method, but because of a conflict with a plugin I moved it into a nested view using Architect. It looks like Architect just didn't delete the initialize method until I specifically told it to do so. So I guess it's more of an Architect issue and personal oversight than anything.