Kotlin code is readable. And this is not a good article to describe kotlin. Kotlin has much more to offer. And syntactic sugar is a great thing. Syntactic sugar is done in such a way that it is readable at the same time. Kotlin has everything what java offers plus modern things. Null safety itself is great instead of half baked solution like Optional in java. Plus Coroutine in kotlin is great for asynchronous tasks and other apps like flow.
I don't know why some java developer act so right and trying to hate kotlin but in general kotlin is not JS. Java ams Kotlin are literally the same things. Woth same concepts of classes, SOLID, design patterns and all. It's just kotlin is offering some better features and it also makes development quicker and less buggy code than java...