Since the advent of the Keychain in OS X, I made sure all ftp site passwords were stored in there... where they will always be available (I back up all my stuff). I used to store passwords in Yummy, but no longer. I suspect there may be some architectural issues, keep in mind that FTP Aliases no longer need the underlying application to function, meaning they are distributable. If passwords were in plain text, they could be retrieved from your droplet.