OK, but where are the advantages? The page has just a different syntactic sugar resembling Pascal/Scala; sine JVM nihil Kotlin anyway. Sometimes Kotlin's "advantages" there have more boilerplate than Java...
For instance, in Kotlin you can perform operations on collection without converting them to a stream first, and collecting them with a certain collector afterwards. So in order to perform a single filtering operation on a collection, you need to do three steps in Java and just one in Kotlin.
Another advantage is coroutines, which not only allow you to write asynchronous code in a common, synchronous manner, but also get rid of shared mutable state, since coroutines can send/receive shared state through channels.
E.g. if you want to parse a CSV or JSON, you would google "how to parse it in Java", not "... in Kotlin". That's different, from e.g. Scala, where everything should be Scala-way (of course you could use Java libs in Scala, but it was always second-class I feel).
Also it is funny to see how Kotlin or Swift are marketed as simple languages when they managed to literally copy 90%+ of Scala features and make some actually even more complex (eg nullability).
If you say "overcomplicated" it suggests you have a simpler solution for the same problem in mind. So, what exactly would you simplify in Scala? Which unnecessary features would you remove? It is easy to throw an "X is overcomplicated" statement but much harder to point to concrete things that could be done differently. Sure, some stuff could be easily removed, but not without making the language less expressive.
I'm now embracing the JVM, and Frege is not an option. It'll be a mid-term transition for me. But it's already nice to rediscover some functional paradigms in Scala and apparently sane design choices when it comes to mixing the object-oriented with the functional style, at least I think I like it better than OCaml.
I'm bothered by Scala's performance as compared with Java. Kotlin's seems to be in parity with Scala in this context, but both by an order of magnitude off from Java's. However, I can't vouch for the "benchmarks" I've come across and I'm not yet familiar enough with either to conclude which features could be detrimental to JVM's performance. I would wholeheartedly appreciate your take on that.
Scala standard library is a bit in the baroque side, but it has been simplified recently in 2.13.
That. There's no "Kotlin way", there's only Java way. That's what I mean.