Platform types are welcome indeed. I am experimenting now with writing a web app using the Ninja Framework (http://www.ninjaframework.org/) in Kotlin. The Java to Kotlin converter has worked well!
But, one thing did not convert, a Java field with the guice @Inject annotation. This is where reflection is used to automagically insert the right object. As this should never be null, I did not want to declare it as possibly null, but had to because using Delegates.nonNull creates a complex Kotlin specific object at the Java ABI level.
This leads me to wonder why the syntax for platform types is not usable in the program itself. In the talks about generics you mentioned that having syntax that only appears in IDE and compiler messages is not great, but here we have exactly that. I could solve my problem if only Kotlin let me specify the type of this field as a platform type.