Kubernetes does in fact need generics. There are types that all work the same but are different types all over the place. For example, you might make a reflector for a v1.Node, and that will call methods on your cache that are like Add(v1.Object), when the signatures should really be v1.Node. Instead, you have to cast the API to your internal implementation. It's not a big deal, but it's a solid example of something that generics would clean up.

I wrote Go for 3 days at my new job and found several places where people opted for interface{} over generics.