From what I've seen in everyone's work is that Go's STD libs are amazing... for the the exact use case that Google has needed.
When you have to deviate from doing anything that Google/Pike would consider "acceptable" for what they would see as the "plebeian programmer" the STD libs aren't built for it. I'd not say it's a side effect of the language (not even the fact that it's lacking generics). I'd just say it's age. It's too young to be refined.