That line of thinking only works up to a certain point. I could say assembly language is simpler, now you don't have to think about functions or basic blocks, you can save your thinking for the problem you're trying to solve! But sometimes pushing complexity into the language instead of onto the users is the better way to go. Higher-level abstractions make things easier. I would rather spend my thought cycles on the business problem, than on reimplementing sum types, or casting interface{} everywhere, or propagating errors by hand.
Certainly, whether or not go has made the right trade offs on simplicity is arguable. I’m not certain whether those features you mentioned would be worth adding to the language or not, but I do know that my experience interacting with Go code has been much easier than my experience interacting with Java code. Haskell & Rust have been fun for me to play with, but they were also harder for me to work with.
Anyways, I can’t give the final word on this question, but those are my two cents.
