They have their stats...
Well, I assume they have usage stats and know, in advance, who'll be affected.
However, I have to think their demographics are more than a little off... if they think they'll only be driving out belligerent, pimply-faced, file-sharing bandwidth hogs that is.
I know quite a few folks streaming audio/video from places like bluebeat or netflix that easily do 25-50GB per month... many of these were the stereotypical grandma-types that used to just stick to email, occasionally wandering off to cnn, etc.
I suppose the old stereotype will still exist but why cater to a dwindling marketshare? Why alienate the rest?