I'm in the SF area and use a DirecTV dish to receive Bell ExpressVu from Canada. (I just happen to be using a DTV dish, but never been a DTV subscriber.) So yes, it is technically feasible.
As to why to subscribe, in addition to the channels you mentioned there are a number of other exclusively Canadian channels. Also, you can get both Boston and Seattle US stations (ABC, CBS, NBC, PBS, Fox) in standard and High Definition.
While DCXFORDGM is correct, much of what he says applies only to those living in Canada. There is no law against anyone in the US subscribing to Canadian satellite companies. There is, however, a Canadian law against the Canadian satellite companies knowingly selling their service to anyone in the US (even Canadian citizens). The Canadian satellite companies are, however, happy to look the other way as people subscribe through "address brokers" who provide you with a Canadian address for a fee.
Feel free to PM me for more on my experience.