That makes perfect seance, for SSH to give up exposing an X server by default. I like the Debian Philosophy of binding all servers to the loopback by default. It just makes seance to start with a secure configuration and then let the users loosen security to fit there needs.
However having the default be insecure as this proposal suggests is not the way Linux development should be done. There are a number of applications that should make use of the 'lock keyboard on me' feature to prevent keyloggers, yes prevent keyloggers from getting password and not prevent keyloggers from being run in the first place. They say an ounce of prevention is worth a pound of cure, but simply not having a cure at all because absolute prevention is the better. It sounds wrong, because it is wrong.
If you work hard to prevent keyloggers from being able to log anything useful, then it makes keyloggers useless. If keyloggers are useless then you'll find there are less ppl using keyloggers. Thus your cure becomes your prevention, it's true that a good defense is a great offense. Make multi-touch vary offensive to any application that attempts to collect sensitive information. On the defensive side the user will do there best to make sure applications like that don't connect to the X server. If you don't do your part the team as a whole will suffer.