Generally it is always better to use public/private keys with SSH, so I guess we didn't even consider passwords. while investigating how to add this, turns out ssh does not natively support non-interactive password input unless using sshpass so given that this is also the first time it came up, I think we won't add this, also since the manual sshfs mount still works as a fallback.
I am curious though why your provider does not support SSH keys?