Adding role-file to ansible-playbook

Since a role file is a great way to download modules from git or galaxy, I was wondering if it made sense to put the role-file option in ansible-playbook?

So, rather than:
ansible-galaxy install -r role_file.yml -p path/to/roles
ansible-playbook mainPlaybook.yml

it could be simplified to:
ansible-playbook -r role_file.yml -p path/to/roles mainPlaybook.yml

Besides being more concise and, therefore, readable, there is an added benefit of any errors being handled by one call, rather than run galaxy, check errors, do the necessary, run playbook, check errors, do the necessary.

I have forked to the repository with a straight-forward change to support this, but I wanted to inquire if it made sense to the design of ansible:
https://github.com/tstone2077/ansible/commit/231e2241fca96d2693dd3dbd73883dcec459c248

Thanks,
Thurston