I don't see these items as being shortcomings. Go is simple and simplicity is elegance, and simplicity is something that cannot be found in most modern languages. Just look what happened to C++, It has become more like C# and Java.
Regarding Nim, I believe it's a nice language and I have done a few small projects using it but just like what I mentioned there are 10000 ways to do a single task and that sometimes is confusing.
BTW C/Go/lua are my languages of choice