I was also using a simple bootstrap script and I too felt I was "killing mosquitos with a bazooka" using Ansible.

But I wanted to symlink my Sublime settings. That meant tinkering with shell code and separating the files in different dirs. Then I wanted to preinstall my Brew apps, but only for Mac.

So these tasks pilled up in shell scripts and became ugly. So Ansible, with it's easy YAML configs, is the perfect tool for a dev like me that wants to setup machines and maintain the configurations synced.