I'm not even going to say why because it would be a huge rant. It improves on C++ in virtually every way. Every feature you have in C++, Rust does it better. Every feature you wish C++ had, Rust has it.
I agree with you on Kotlin. It's better than Java on paper, but in much the same ways Groovy already was. And the advantages are shrinking in new versions of Java, especially if you use Lombok.