That's the really disappointing part. I've read the thread where the designers talk about implementing generics, and they basically say that every language's implementation of generics sucks, and since they can't come up with a design that's perfect (no codegen duplication, but still all the perf of specialization), they're just gonna punt.

And then the code I've seen is littered with "interface {}".

That's a pretty big thing to give up, and I don't get the point. Something like F# gives you high level features (and green threads if you want) with fair perf, and Rust gives you a fair amount of language with C perf.

I think littered might be a bit strong. I'm writing a service in Go, and have yet to use interface{}. However, you might have to use it more when writing libraries.

That's false. Go has structural subtyping. It enables you to sort collections of things without actually writing a sorting algorithm. Seems like generic code to me.

It has interfaces to write generic code. It doesn't allow you to write your own generic data structures but it's not an issue because it has built-in dynamic arrays and dictionaries. You supposed to use built in data structures most of the time like with python or ruby.