As others have noted, "Canada Day" is about as banal a name for the celebration of a nation's (official — in most important ways, Canada is a great deal older than 142 years, but that's a rant for another time) coming-into-being as can be imagined.
The Americans have Independence Day, not America Day; the French, Bastille Day, not France Day; the Germans, Unity Day, not Germany Day ... I think those three examples alone serve to make the point.
Canada is short-form for this country's full name, the Dominion of Canada, a phrase of historical importance with a Biblical allusion and a certain poetic gravitas.
"Canada Day", by contrast, is a-historical, utterly prosaic and completely lacking in imagination, suggesting to me a weird kind of self-loathing that implicitly denies there is anything worth celebrating in a day that is meant to be, well, a celebration.
"Canada Day" is a name that should be retired as a first step towards reclaiming our history, towards facing both the good and the bad within it.
Still, 142 years of unbroken constitutional history that has led to one of the most interesting and ever-more dynamic cultures in the world. I'll raise a glass, whatever the nomenclature.
"A Mari usque ad Mare!"