I’ve been using ktor in a personal project and it’s been a joy; all the familiarity of Spring but with Kotlin first.
Also, I know that Amazon has started to switch some projects to Kotlin, since they’re such a large Java shop: https://aws.amazon.com/blogs/opensource/adopting-kotlin-at-prime-video-for-higher-developer-satisfaction-and-less-code/
Big Kotlin fan.
Similar reasons to the commenter that talked about using a world class runtime, but the JVM is tested and works.
And now I can use Kotlin to make cross platform applications, while still utilizing the Java knowledge that I unfortunately possess? Perfect!