I’m sorry, but null restricted types, string templates, basic json support, and fixing the broken exception system isn’t “fat”. They’re the basics of a functioning language.
Handling JSON as a basics for language? Really? null restricted type will come with valhalla, string templates had a try, but people complained and they withdrawn them after 2 preview iterations. Not sure what issue people had with them and what issues maintainers noticed.
What do you mean by broken exception system?
Java is not a small language that you can throw features around, they have to take into consideration final goal of it and decades of development.
Null restricted types are indeed important and while null check plugins exist for Java, this is a big step in the good direction by kotlin.
String templates are valuable syntactic sugar, but that's it.
There are a bazillion JSON libraries with at least 3-4 absolutely stellar ones. I don't really see it that big of a limiter.
And if you mean checked exceptions, that's controversial to claim it's all bad. But some ergonomics improvements would be better.