The comparison is against Python, which definitely has better ergonomics and includes everything needed for scripts like this (but does have package management too if the huge standard library is not enough).
I disagree that Python has better ergonomics than Rust for scripts like this. For example, IMO python doesn't have anything as nice as Rust's structopt library for argument parsing (https://github.com/TeXitoi/structopt). Python does have package management, but it's a pain to use compared to Rust or JavaScript (have to setup virtual envs, etc - not very ergonomic!).
You also mostly don't hit into the tricky ownership issues that can make Rust less ergonomic in CLI apps. Because the code flow is usually quite linear, so you don't have multiple bits of code trying to access the same variables at once.
Note: Although Rust has static types, it has very good type inference such that you don't often have to explicitly state the types. IMO this brings Rust pretty close to dynamic language ergonomics for simple things like this.
Python has argparse in the standard library which does everything you may need and more. You can even make Git-like interfaces with it.
For most CLI tools you do not even need third-party packages in Python to begin with. You cannot beat that. And if you do, you don't need virtualenvs, because your system package manager can do the job just fine for most cases, or you can use pip or you can locally deploy.
Python has no ownership issues to think about. You cannot beat that either.
Type inference is nowhere close to dynamic typing.
Then there are other things like no compile-edit cycle in Python. No binary distribution. No shenanigans like issues with missing libraries and dynamic linking.
So you may disagree, but your points are not valid. The actual advantage for going for a compiled low-level language is performance, so unless you need that, there is no point on using Rust or any other compiled language for the majority of the boilerplate code for small scripts and CLI tools.
You also mostly don't hit into the tricky ownership issues that can make Rust less ergonomic in CLI apps. Because the code flow is usually quite linear, so you don't have multiple bits of code trying to access the same variables at once.
Note: Although Rust has static types, it has very good type inference such that you don't often have to explicitly state the types. IMO this brings Rust pretty close to dynamic language ergonomics for simple things like this.