I can see why you might say based on the Canadian cloistered view of the world. But, yes, if you had the border problems that the united states, europe, africa, and south america have you would see that having the united states is a "favorable neighbor." If you suddenly woke up tomorrow and venezuela or mexico was on your southern border, let's just say it would be "different," eh?
As far as Canada "taking" California, keep in mind that both the population and the GDP of California are greater than the entire country of Canada. More likely, the United States will just annex Canada some day for extra storage space or to have a secure supply of maple syrup or something.