Let's not forget that the JVM still does not have reasonable generics & value types. The .NET CLR introduced this in 2005, bettering the JVM. Java was in a sleepy slow release mode back then. We've been waiting 18 years for value types and proper generics - Valhalla has been just about ready for a very long time. Some of us moved on a long time ago.

Agree that Kotlin is a bright spot in terms JVM languages. For my taste has adopted some of the best concept of Scala, but without the burgeoning complexity.