Seems fine to me

That is the one thing that really keeps me from using go

When would you need generics and not be able to use interfaces instead?

For example when I want to implement own containers (Set, List,...) or when I want to write Elastic search queries. There are so many usecases where generics are usefull. It's the same problem I have with C. I just don't have the typesafety I want and need casts everywhere.