>> "I tried it - it puts 50MB of DLLs beside HelloWorld"
That's a bad test for a framework. It's like saying, "I bought an $80,000 car to drive to my neighbor's house across the street - I could have just walked!"
A good test is, "What is the full install size of a real app built on .NET Core?"
And the answer is, not much larger than any other app. All that code has to live somewhere, either in your app or in your libraries.
I tried it - it puts 50MB of DLLs beside the "HelloWorld" executable in a subdirectory (on Ubuntu 16.04).
It's like shipping the entire Java runtime with every app.