You can compile Kotlin to Javascript, as a start. You get the benefits and drawbacks of static typing and object-oriented (or rather "class-oriented", if we call Javascript object-oriented) programming support.

But if you choose to stay with the JVM, you get:

- the JVM - multithreaded, highly tuned and high performance JIT VM, well documented and continuously being improved

- mature tools

- libraries from the Java ecosystem - for pretty much anything you can think of

- coroutines (with Kotlin 1.1) for async support.

XML configuration is being phased out slowly (I guess you are talking about Spring here), in the last ~10 years annotations have become much more popular. You still have to support those legacy apps though.

This made me laugh: "then I thought of Java and images came up in my head of thousands and thousands of files being installed" - well, don't check your node_modules directory then, or you might be in for a surprise :)