We have a lot of use cases when we need some files in debug mode, but we don't need them in release builds. I've seen following in final packages: - *.d.ts - *.md - *.html (it was HTML help of some angular packages) - tests - unit test runner (https://github.com/NativeScript/nativescript-cli/issues/2773) Adding such feature will help users to optimize app size of final package.