Okay, let's say I agree with your arguments:
1. Go "is still not as fast as Java can be" [1]
2. "Go lacks the most basic tools which any seasoned developer can expect from a language (like generics)"
3. "Go does not have a de facto build system and you can’t handle dependency management in an easy way" [2]
4. odd error handling
5. not a lot of libraries to choose from [3]
6. possibly more arguments that I missed when summarizing your post
The way you paint it, people would be stupid to use Go. However, thousands of very talented developers use Go everyday. How can you explain this disconnect?
[1] I like how you didn't say that Go "is not as fast as Java". That's a subtle, but important difference.
[2] `go install` is the build system and I have solved dependency management for myself with literally a small shell script [4], and an official solution is in the works [5].
[3] I never had trouble finding libraries for use-cases both common and obscure).
[4] https://github.com/holocm/golangvend
[5] https://github.com/golang/dep