I disagree with the article, but also some of these examples are complete straw-men. In Kotlin you have nullable types, and the type checker will complain if you use it as a non-nullable type. But you can always just append !! after your expression and get exactly the same behavior as in Java and get a null pointer exception, you don't have to handle it gracefully as the author is suggesting. Tests checking that you gracefully handle nulls in a language without null types are fucking tedious and boring to write. I would take a language with null types over having to write such tests any day.

Kotlin's final-by-default is also just that - a default. In Java you can just declare your classes `final` to get the same behavior, and if you don't like final classes then go ahead and declare all of then open.

I also disagree with the author's claim that languages with many features requires you to be a "language lawyer", and that more simplistic languages are therefore better. It's of course a balance, and there are examples of languages like C++ and Haskell where the number of features become a clear distraction, but for simpler things like null types and final-by-default, the language is just helping you enforce the conventions that you would anyway need when working with a large code base. In dynamically typed languages you just have to be a "convention lawyer" instead, and you get no tool support.