[spion]

Thats not a strength of Go. Structural interfaces, channels and performant M:N green threads are its main strengths, and AFAIK there is no other language that provides a similar combination in a familiar C/ALGOL-like packaging.

If such a language existed and had generics and Swift or Rust style error handling as well as some backing by a large-ish corporation / organization, I think that language would be preferred to Go.

More expresiveness isn't always better. Examples that hit the sweet spot are C# / Swift (C# really needs algebraic data types). Beyond a certain point, you will start to lose users. Haskell is very expressive, but few will ever have the time or patience to learn enough to build their perfect monad transformer stack and take advantage of the mtl typeclasses to easily use it. Even though it does have M:N green threads, channels, STM and everything.

In fact, Haskell could probably compensate for this and beat Go by having excellent library documentation and well written, focused tutorials for the working engineer.

[reikonomusha]

I feel like maybe 10 years ago no one would utter something like "C# needs ADTs" because they didn't have mainstream appeal, despite computer scientists' understanding of them.

[spion]

Yes, things are moving forward, even if slowly :)