How would you take a template file, fill in some values, copy it to a certain path on the server and give it the right permissions? With, say, Python, I'd have to read the file, using mako or jinja to fill in the values, scp the file to some temporary file, then somehow run Python code on the server using SSH to copy the file and give it the right permissions.
Let's see... I would take the template file, fill in some values, scp it up to it's final location on the server, and run chmod on the server.
I guess I could learn the "one-line" ansible way to do it, but I'd also have to learn to set up ansible. And I'm guessing it's not as flexible as, say, shell scripts.
The cool thing about Ansible is that there's no set up. You install it, write the config and run "ansible-playbook <config>". It connects to the nodes using SSH and runs without having to be installed in them.
As for not being as flexible as shell scripts, I'd say that's technically impossible, since it has a command for running shell scripts :) Personally, I never had to use it, but it's there.
With Ansible, this is a single line.