It is is a pretty large cap, but it’s clearly designed to profit from high-bandwidth users. There’s nothing inherently wrong with charging bandwidth hogs for their capacity; plenty of businesses charge on such a consumption model. The issue comes when this directly affects the ability of video-streaming sites like Netflix to carry out their business model, because of the cost-prohibitive nature of the service for individual users. Just three hours of HD video on Netflix would wipe out the entire 150GB monthly limit, for example.