I can see how you might have come to those conclusions regarding Canadian news reporting having seen a fairly small snapshot of it in recent years, and also viewing it from the perspective of suspicion and cynicism you probably have with your national media. It's possible that Canadian media may have devolved to the point that you're arguing, but it's been so gradual that I've not noticed it. I think though that you have to take an historical perspective to tease out the answer, and a large part of it comes from our national identity, or lack thereof (although I don't think the latter is really as true in recent years).
Consider Canada for a moment, a large landmass with approximately a tenth of the population that the US has, a relatively new nation. In comparison, the US is like this behemoth, one that is always threatens to suck us in culturally, not in a literal sense, although that looms to a certain extent, too. This especially holds true considering that the vast majority of our population, unlike yours, lives very close to the US border.
I was a young child in the 70's, and I think I was somewhat precocious regarding pop culture, but I remember a lot of it fairly clearly. I recall growing up that there always seemed to be this sense of inferiority and America-envy regarding many things, media and entertainment included. We didn't have the variety of Canadian television broadcasters that we do now. Certainly, the same can be said for you guys, you've vastly increased as well, but when the numbers are shrunk down proportionally, you still had a lot more than we did. We essentially relied on the US for entertainment. In the area of music, I can remember a handful of homegrown Canadian artists, but that's about it. Of course, that's what led to the development of the much maligned Can-Con rules by the CRTC in the early 70's (I can't remember that specifically, but I do remember what we had at the time, and what the ensuing decade or so was like). From that time on, our music scene has flourished, and despite the criticism that Can-Con receives, I can't help but think it created positive change. Would the industry have developed on its own without the help of government rules? Probably, but I think it would have taken a lot longer. My digression aside, my point is essentially that in the area of media and entertainment, you guys were the giants we relied on until the government intervened, and forced Canadians to be exposed to Canadian entertainment.
In television, and in news broadcasting specifically, in the 70's (the dark ages, before the advent of remote controls, when you had to get up and physically change the dial on the tv) when we watched American television, I suppose some people would have gotten their main exposure to American network news by turning on the channel to view whatever was on after the news finished, not necessarily out of a specific interest in US news. I'm sure many others though, specifically sought out Canadian networks to view their news on.
As for the sheer amount of American coverage on Canadian-based news networks, I have a feeling it's partly to do with the vast size of your nation, in terms of population, thus, the amount of news generated, as well as the great impact that America has on world events overall, along with our close proximity to you. As I alluded to earlier, you may be right, there *may* be an element of "look at them, we don't have it so bad, do we? Now sit down and shut up" implied in much of the US news we receive, but I don't think that's the main motivation. I freely admit that since the Iraq war, there has probably been a certain smugness involved in some of the news about the US that originates from Canada. Sort of "how the mighty have fallen - remember when we used to envy them?" However bitchy a reaction that might be, I think that reflects more on our (mostly former) sense of inferiority regarding the US. Unlike you though, I've never gotten the impression that our news broadcasts air American news to the exclusion of Canadian news. To me, it's always been more of an "in addition to" scenario. I also think that our news broadcasts tend to be more straight-on, factual reporting, without much editorializing.
The main reason I think that Canadian events aren't reported so much on American network news, with the exception of brief mentions in border town affiliates, is mostly because of American-centricism. I don't really use that term in an insulting sense. The fact is, your nation is so large in comparison, so complex, that you don't need filler for your news broadcasts. Couple that with the trend in American news to analyze every minute detail ad nauseum, and there isn't much room for other nations to be covered in any depth.
One final thought before I have to sign off - maybe it's not that Canada spends a disproportionate amount of time covering American and other international news and events, but that America spends a disproportionate amount of time *not* covering them? During bouts of insomnia in recent months, I've had to opportunity to watch on a City-TV news channel late night broadcasts of European-based news programs from countries like France and Germany. They seem to be more equivalent to our news, in that they cover a lot of international news.