(Full disclosure: I'm the developer of clize, another argument parser)
you usually don't want to do a pip install just to run a script
I feel like this should be corrected instead. While I'm not advocating script developers auto-install packages, it'd be nice to help "I just want to ship a single 50-line file" people make better use of dependencies.
What if they want to use `requests` (of which the maintainer is, as I understand it, leaning on the side of not including it in the stdlib) ? It's even more likely than wishing for a different argument parser. I'm sure there are other examples.
Including another lib in the stdlib (of which there are already 3 alternatives in!) is merely delaying this general issue.