For people outside of US, where we don't have service providers that screws us sideways, this is a negligible problem. But I can see the point for people who are routinely being scammed by their service provider.
I have cable internet in Quebec and the cap is really low. 120gb a month is to me quite low. I watch most of my tv,news,sports online now and I have to actively monitor it. Does nothing to reduce my total bw rate usage while I'm streaming. I guess my usage drops at the end of the month. It still doesn't help their claimed problem of congestion.
120GB is low, but not nearly as low as other limits I've heard of.
I'm in Halifax, and the ISPs here seem pretty decent. Bell Aliant doesn't have caps at all - they used to be a distinct entity from Bell, IIRC, and are still sort of separate from the Bell that's often mentioned - and Eastlink caps at 250GB, or were planning to a few months ago anyway, but that's only for their 50 and 100 Mbps plans. The normal, standard-in-a-bundle plan is 20Mbps and is uncapped. I've been pretty pleased.