Those things don't require noticeably more code to automate with SFTP than with FTP, or need a more complicated interface. Maybe nobody has written that code to make the management easy? Someone that cares about security should then.
Google suggests that some servers can do SFTP with virtual users.
FTP is perfectly secure though when run over SSL (FTPS), so why not use the protocol that’s already designed for file transfer with the server that makes it easy?