Fury, I have some of my own input on this as well. Also, my opinion is loosely based on current events and a majority of personal feelings. This is just my opinion.
I think the US, in particular, the citizens, see Canada as the little brother. We've become so accustomed to Canada just 'being' there to support the US. In ways, I think we take Canada for granted because its military history is not as indicative(on a superficial level) of a super power as the US's is.
This however doesn't justify 'how' we came into power, 'how' we use our power, nor does it justify any claim that Canada is not a strong nation. I for one have met many Canadians and they are a great people. I think Canada's presence in the global theatre is greatly under rated, and I for one, would like to see relations between the US and Canada remain a strong one.