You're mistaking familiarity for simplicity. You cannot get much simpler than the lambda calculus, full stop. It has three concepts--lambdas, variables and application--and one evaluation rule. That is all. The rest of the language features are almost always just a thin layer over this.

Even when you add types, it's still an amazingly simple model. And the types do not generally affect the runtime behavior of code at all.

Functional languages are the very picture of something simple but not necessarily easy. Go, at least for you, is the opposite: it's easy because it's similar to what you're used to, but it also has quite a bit of surface area.

My impression is that Go vies for simplicity of implementation over simplicity of semantics. It is a very operational sort of language. Its goal is to make the how clear--the code reflects what it does.

Languages like Haskell, on the other hand, are completely the opposite. Haskell values simplicity of semantics over simplicity of implementation. It is a very denotational sort of language. Its goal is to make the what clear--the code reflects what it means.

It's a difference in philosophies, certainly, just not quite in the way you construed it to be.