Go solves a very specific problem: the limitations of Python, CPP, and Java within Google. That's it. Google maintains control over the constructs within it in order to standardize its (Google's) code. When only Google's code matters, there's no rationale for things like including generics and or consensus standardization via ISO.

That's not to say Go is bad. There can be a lot of overlap between the type of problems Google designed Go to solve and the types of problems other people and organizations often have. A lot of people write systems code. A lot of people experience the limitations of Python, CPP, and Java. Not everyone of course. I mean to me, the Go ecosystem looks so much like an "enterprise" decision that it would be mocked by the very people using it if Go came from IBM or Oracle.