Disclaimer: I'm still not sure I understand fully what setup.py does.
From what I understand, using a setup.py file is convenient for packages that need to be compiled or to notify Disutils that the package has been installed and can be used in another program. setup.py is thus great for libraries or modules.
But what about super simple packages that only has a foo.py file to be run? Is a setup.py file making packaging for Linux repository easier?