Frankly, after 40 pages of responses, I was too lazy to read through them all. This argument might have been made before so I apologize if it's merely a repeat, though, the question was intriguing enough for me to want to sign up and chime in.
I saw a couple responses denoting that people want more symbols to believe in, and that republicanism is reflective of democracy. While theoretically true, voter turnout these days everywhere, not just in Canada, point to the fact that symbols no longer enthrall the populations of democracies like they once did.
Indeed, people seem to fall in love with the idea of a republic over the symbology alone, as if creating in Canada that catch-all phrase republic would somehow turn around the democratic malaise that, is frankly a lot worse in places that do indeed declare them to be said republics.
The fact is, when we talk about transforming our political system, it won't be in name only. We have to recognize that the very essence of the political legislative process will be changed. People fantasize about the system of checks and balances but in reality in the United States those checks and balances do a lot more to harm the process than to help it. People hate government because it gets nothing done and fosters corruption and massive redundancy in the bureaucracy. The mere fact that there are so many points in the legislative process to kill legislation to "protect us from tyranny" allows private interests to easily bribe congressmen who aren't bound by parliamentary discipline and said reps (or other bureaucrats from powerful deparments *ahem* pentagon *ahem*) can easily add spending into legislation to get it passed (porkbarrel politics). In the end, this does happen in Canada but in no shape or form is anywhere close to the leve it occurs in the United States.
The republican system cripples the legislative process in that legislation moves at a snails pace in comparison to that of the HoC in Canada. In the end, this has to somewhat influence electoral politics. In the technological age people and information move at the speed of light and in the end Americans can't relate to their 18th century political system because it can't keep up with society. Look at the health care debate. Though a clear majority of Americans want changes to health care, the entrenched interests in Congress with funding from the AMA and the Health Insurance lobby will more than likely kill any attempt at health reform. In fact, the fastest thing that the congress has done in the past ten years was to approve a motion to sing the anthem on the steps of the capitol after 9/11. After that, everything is a dog fight.
In Canada, if there's a majority, which Canadians are now again craving, the government can get down to business and get things done. In the end, Canadian democracy is entrenched to the point that if a majority government is doing thing that the population resents, they can be kicked out (Mulroney) and we don't need checks and balances to keep us from giving ourselves a dictator.
For those people who use regional differences and decentralization as a means to gain a republic, honestly, the west has merely taken a huge sip of the Alliance/Reform/Conservative kool-aid. Regional differences (with the exception of Quebec) never factored in to elections to the point that they have until Stockwell Day, panicky as most Conservative leaders are, started airing ads that the east hated the west even though Chretien's ads were a pan-canadian message that didn't change from riding to riding (which Conservative ads did. Clearly the we love Ontario ads during that period were never played in Calgary. Thank god we got the real message when Mr. Baird told Toronto to Fuck Off). Since then, the only way the Conservatives have been able to get in is to play on that regional divide rather than strengthening the unity of the nation. In my opinion, thats as bad as seperatism.