Complexity and a probably the wrong word for Rust. C++ is certainly more complex. However Rust requires you to think a lot more. It has more theoretical concepts. It is more academic if you will.

Let me put it this way: C++ is much more complex than Haskell, but so will claim learning to become productive in C++ is much faster. The minimal concepts you need to understand are easier to grasp.

Rust leans more in the Haskell direction.

The simplicity of Go is very real though. I have frequently looked at Go standard library code to understand how different things work. It is way easier to read than typical C/C++ code, Java, Python, JavaScript, Swift or Objective-C.

Although Julia is my favorite language, I don’t think it is always as easy to read as Go code. It allows too many fancy things.