It's pretty simple -- those of us who use those feature regularly in other languages know how valuable they are, and we miss them when they aren't there.
Is that really a problem? I think proper sum types to allow Result types that can encode many success/error states are so much nicer than an exception hierarchy. Rust and Kotlin did not go with exceptions, and for good reasons.
> C, C++, Java, Lisp, Python, Ruby... you name it I've done it.
Let me name a few: Rust, Kotlin, OCaml/Reason, Haskell, Elm. These languages carefully selected a set of features, the all have: no implicit nulls and sum types. And in your list non of them have those features. I really wonder what you think of these features when you've worked with them.
Kotlin very much did go with exceptions except for the Result type in coroutines which wraps a Throwable anyway and is only used for the border between the coroutine runner and the async functions.
I've had a long career coding in C, C++, Java, Lisp, Python, Ruby... you name it I've done it. Go is my favorite most productive language by far for solving typical backend issues. My least favorite? Java by a HUGE mile.