I have to add my voice to the choir calling for generics to be added to Go. As others have noted Go contains no fewer than four parametrized types: arrays, slices, maps and channels. Such types are so mandatory that it seems impossible to build a programming language without them.
And it is an annoying asymmetry that I as a programmer can't define an equally parametrized linked list or binary tree type. I expect that these will come eventually. My hope is that it will be sooner rather than later though.