I think do like moving these out.  Having vars here _seems_ useful for defaults, but ansible's variable precedence rules for variables defined in "playbook-like" environments (vars in playbooks files, var_files in playbook files, vars directories in roles, etc) are sufficiently murky that it becomes a bit confusing what becomes defaults and what are overrides.   As I read it, the third paragraph http://ansible.cc/docs/playbooks2.html#understanding-variable-precedence pretty much puts all of these in the same tier, with some not-fully-intuitive ordering imposed, so it sort of makes me a bit shy about hash merging between say a var_file and a vars/main.yml .

That's a long winded way of saying I think it's best to cut these example defaults out, though I wish we didn't have to.