The problem with Python is that it’s really hard to distribute a Python app to users. Nothing beats Go’s ability to compile into a self-contained binary.
Python is also slow and has poor support for parallelism.
Finally, “Python is simple” only really applies to its syntax. Overall, Go is a significantly simpler language than Python.
"Slow" isn't a typically big deal for CLI apps, but Python culture tends to do a lot of work on initialization, and I've consequently seen a lot of Python CLIs that take nearly 10 seconds to print --help. Because the way most apps and libraries are written, you end up loading and initializing every single library that any part of your CLI uses, even if the subcommand in question doesn't use those libraries (e.g., printing --help). This is solvable via lazy imports, but few go through the hassle of doing this, especially since it makes the code ugly and non-idiomatic.
I do like Python, but I think Perl is actually designed (and actually is) a super-charged bash. Perl was created with the purpose of simplifying the combination of bash + awk + sed + grep, a goal it has achieved quite well.
Python has better OO and has won more mindshare than Perl, but I don't think it was ever meant (or accomplishes the goal) of being an "overcharged" bash.
Python is also slow and has poor support for parallelism.
Finally, “Python is simple” only really applies to its syntax. Overall, Go is a significantly simpler language than Python.