I've used Java and Go. I find Go a far superior experience. Part of that is the standard library which seems to strike a perfect balance providing what you need but not too much.
I also think a lot of it has to do with the culture of the languages. Kotlin is a pretty nice language, but using it for Android still makes me want to hit my computer with a hammer because the over-abstraction of the Java ecosystem is maddening.
That's definitely the path they're headed towards. @FunctionalInterface from Java 8 and type-inference from Java 11 and instanceof destructuring from Java 14 are the big changes.
"Proper" modern Java is functional, at least at the surface level.
The big issue is that the ecosystem is kind of stuck; it's freaking 2021 and we're still targeting Java 8.
Also the type system could be better, null references are everywhere even though there is Optional<T> (I wish it had optional strict null checks a la Typescript, but I'm not sure how realistic that is), and the fact that you can't have List<int> because generics won't work on primitives is just boneheaded.
But yeah, the language isn't the "Dog extends Animal" bullshit they teach you in school, at least not anymore.
It doesn't matter. Eventually you will need to use some library that's from the old days. You can't escape the abstraction. Not everything has been or can be updated to modern standards so just like C++ eventually every bit of the language ecosystem will come back to haunt you.
Go doesn't suffer from this yet because it's too new and the philosophy is different which keeps some of it at bay, but it's only a matter of time. Entropy always wins.
I also think a lot of it has to do with the culture of the languages. Kotlin is a pretty nice language, but using it for Android still makes me want to hit my computer with a hammer because the over-abstraction of the Java ecosystem is maddening.