FYI there is already tool with functionality you implement: ssh-copy-id. This tool is available OOTB at least on Ubuntu and can be installed on OSX with brew install ssh-copy-id.
brew install ssh-copy-id
Although it won't generate key pair for you.
Yes, if I'd have known about it I never would have built this tool!
Fancy sending a PR with a patch for the docs?
Update readme to mention ssh-copy-id