I've said this before, but much of Go's design looks like it's imitating the C++ style at Google. The comments where I see people saying they like something about Go it's often an idiom that showed up first in the C++ macros or tooling.
I used to check this before I left Google, and I'm sure it's becoming less true over time. But to me it looks like the idea of Go was basically "what if we created a Python-like compiled language that was easier to onboard than C++ but which still had our C++ ergonomics?"
But certainly, anyone will bring their previous experience to the project, so there must be some Plan9 influence in there somewhere