You do not know what you are talking about.
While that might be "a" way to change the password, the MobileTerminal program provides a convenient shell from which passwd works just fine. It is strongly recommended that the root and the "mobile" accounts' passwords are changed from their default. Instructions for doing so abound even with screen shots for people who can't be bothered to read. While there is the "hassle" of having to install MobileTerminal, I'm not sure this is really too much trouble for someone that has gone to the effort to jailbreak in the first place.
That being said, Saurik should be able to make the installation process for OpenSSH ask the user to change the passwords. It also should not be enabled by default, or turn itself back on after it is turned off (in my experience the OpenSSH program has a tendency to do both).