I guess that the complexity people are concerned about is that once you implement a parametric polymorphism, HKTs are inevitable and that probably requires some brain flexing in order to get the meaning of a structure, which defeats the main purpose that is being explicit and simple. Pretty much a deadlock. I now understand why the community is so in odds with the parametric polymorphism as the concept but I'm also sure that simplicity of use and convenience of writing a robust solution is the two things that require it. You can't keep your head near the sand and avoid HKTs when you want flexibility and you can't allow that type of polymorphism whilst striving for what's Go trying to do.

While understanding the both standpoints, though, I still hope that Go will get parametric polymorphism as it's just so much more pleasant and convenient than carrying around a mess of structures to be explicit no matter the costs.