Why shouldn't it be as easy to write system administration programs in Go as it is in a typical shell?
1. Shell scripting offers infinite functionality. You can shell script with any program in any language. All it needs to do is take input and produce output. And if the functionality doesn't exist, you can create it on the fly, without having to follow any of the traditional rules of programming.
2. Shell scripting is a combination of a grammar, operators, a few simple functions, and an extremely loose coupling with generic i/o and logic. I don't know Go well, but it probably doesn't support a similar flexibility. (most languages are very proscriptive about how you can use the language, so you usually can't make things as easy as they are in a different, more tailored language/interface/paradigm. this is why we have DSLs)
3. Programmers don't really understand the concept of productivity [outside of programming itself]. A programmer would solve a problem by taking 6 weeks to design a perfect program to do the thing. A Sysadmin would take 5 minutes with a shitty language and a shitty tool and get way more done in less time. And re-writing everything into a Go library would always be slower than shell scripting, because it requires re-implementing what a shell script would just use as-is.
Scripting is duct-taping the wheel rather than reinventing it. If you want to save yourself a whole lot of time and trouble, just use the duct tape.
(also: don't go templates exist? why isn't that used for scripting)