Well, as said before sometimes you need it because pip isn't installed by default.

Just had such a situation yesterday at work. A guy from QA (not a dev) needs to setup an environment to install our tool for testing. He doesn't know python, so explaining to him what a virtualenv is would take way too much time. He probably also doesn't know how to use the OS's package manager to install pip. So, what to do? Give him the oneliner "$ sudo easy_install whatever". It works, he doesn't need to understand it, and actual system maintenance doesn't matter because it's just a VM that gets deleted after he's done anyways.

You don't. First, if your QA peeps can't figure out an OS package manager, they need training. It's also a one-liner.

Without a package manager it is only a two-step process. 1) download get-pip.py from the source 2) run it with sudo