It's disruptive in the same way me shouting at you while you're trying to get work done is disruptive.
[ For that matter, 9/11 was pretty disruptive, but I don't think that terrorism is a good start-up idea. Please refrain from knee-jerk reactions (i.e. "I can apply the word 'disruptive' here, therefore it's good"). ]
What benefit is there from changing functionality that's worked for decades and not documenting it? This is core Ubuntu functionality that they changed, and they did not document it.
So, what you're saying is that this new motd system is some seriously disruptive technology? Good on those ubuntu kids, showing us all how its done.