The handful of discrpancies we all know of aside, the Governer General performs tireless duties on behalf of the Canadian People almost year round, representing our goodwill toward allies and reassuring them of our commitments. If she or he did not exist, it would be the Prime Minister who would have to do all that ribbon cutting instead, and in my view that's a waste of his time. We need him (or her) to actually run the country and worry about policy.
I for one am not ready to just dump our heritage for nothing. Canada is a free country just like our Commonwealth cousins who share our Queen. It's a Francophone country just like Belgium, who also has a Queen. A progressive northern country like Sweden, Denmark, Norway, and the Netherlands, which are all constitutional monarchies. Having a Queen or King as an expression of our heritage does not take anything away from us as a country, it only adds to the richness of our identity. It also is yet another huge thing separating us from our neighbours to the south, which heaven knows is something we will always need in our struggle to maintain our sovereignty over this great land. And what an added bonus that we don't even have to pay for the Queen. The Brits do that for us. We just pay for her representative in Canada, who is in turn our cultural ambassador to the world.
To the fellow who has a problem swearing allegiance to Her Majesty and her successors... tough. If you really wanted to be Canadian you would accept this country for what it is, a constitutional monarchy with a prime minister, a governer general, and yes, a Queen. If you want a president, I suggest you either stay where you are, or choose another foreign country to adopt as your new homeland.