First, Canada government is not a master of anyone, nobody has the obligation to be loyal to it as a slave. This is not one of requirements to apply citizenship. Anyone can criticize it freely.
Second, for me Canada is not an "opportunity" of life, it's simply one of many options, I was begged by the country's business to come here because they wanted my skills. I had wrong impression by the propaganda of the government and made wrong choice to come here. I paid hundred thousands of tax to this country and I regretted. I'm actually in the process of relocating back to my "home" country, which is much more economic developed and civilized than Canada in terms of laws and orders and human right conditions. So please don't assume everyone coming to this country desperately.
One of examples, in my home country, anyone including immigrants can challenge government for unfair laws and they often won and even got compensations. But this is unimaginable in Canada. Among the immigrants in my home country, a lot are Canadian from birth, they complained to me a lot about Canada before I came here but I ignored them and now I regret I should have follow their warnings.