As a Scala developer I heavily use generics, but generally only when writing libraries. Application code, code that becomes the final executable and isn't mean to be reused, is usually very light on generics and many other fancier aspects of the type system. Perhaps it goes without saying, but it's only when writing generic code do generics really become important.
To me, Go seems good for one-off projects like this. The code is straightforward and it's small enough that it's not a big deal to hand-write functions that could have been generic. But for large projects or for writing highly reusable code, Go seems really unfit for the job, and I think it's those kinds of projects people have in mind when they criticize Go for not having more powerful features like generics.