In C# I feel you needed generics because there was no resizable array without casting from object (the Pareto 80-20 use case) and later async and Task<T> but I don’t think these problems apply to Go so it could have done without it (maybe!). Non userspace generics may be where it is at to ease suffering in places.
As a language design though Elm remains remarkably simple with parametric polymorphism (aka Generics) but it needs other design choices to do so. Elm is the Go of Haskell :-)