No political party wants you to be free. They want to control you, they want power over you.
Governments want to force thier will on you. Would a Republic of Canada be any different than the current Canada?
We're talking symbolism here. The Queen is an unrepresentative, unelected, undemocratic, unegalitarian, hereditary institution that harks back to the medieval era.
The political philosophy behind republics are democracy and egalitarianism.