Well it surely is an interesting discussion going on here.
My background: I am newcomer to Canada myself. I am an Indian and have lived few years of my life in UK and Germany before arriving here.
Now, I really don't know how COC as a concept would fare when taken through the trial of legality. But I totally understand the feeling behind this concept, and why some people are raising this issue. But from where I look at it, I find it really weird that someone can get a Canadian citizenship just after living a few years at stretch and clearing a citizenship exam. Some of you might not agree with me, but for me Citizenship means much more than a certificate or a passport. Citizenship means that I am emotionally invested in a country.
For me, nationality is not just about privileges and a powerful passport.
Let me tell you an example. I have a colleague at work. She is an Indian by birth, but a Canadian citizen for past few years.
I was just pulling her leg one day by throwing some simple questions about Canada. I was amazed to find that she could not even tell me the number of provinces in Canada. She did not even have a clue of approximate population of Canada. Looking at this, I did not even bother asking her more about some recent Canadian history. Now to me, she is clearly a COC. Being an Indian, I would be absolutely furious if someone came to India, lived a few years and obtained Indian citizenship even when they had no clue of what India, as a country is.
I have seen some immigrants giving some really stupid reasons about why they became Canadian citizens, one of it being that on Canadian passport they can travel almost everywhere Visa free. Having seen such people, I can totally understand why some of the Canadians are unhappy about the current state of affairs.
Unfortunately, COC, as a concept, is so complex that it will be really really difficult to put it in definition. But, in principal I totally agree that Canadian citizenship should have more value. And that it should not be so easy to obtain it. Citizenship should not merely be about living a certain number of years and clearing a stupid test. Immigrants should be asked to invest themselves in Canada, make sacrifices, like giving up their original citizenship to show that they really value and take pride in Canadian citizenship. Such steps would also take care of people who abandon Canada after becoming citizens, and keep this passport as a backup for a rainy day.
Restricting mobility post citizenship is really not a solution. It will be tyranny. Putting a ban on dual citizenship and taxing based on citizenship are surely a way to fix some of the issue, if not all. A number of countries already don't allow dual citizenship, and for some good reasons. India being one such country.