Myself I came to Canada for economic reasons but that does not mean that I am completely going to forget where I came from. If I so wish, I can decide one day I don't want to live in Canada any more and I want to go back to my home country. What is wrong with that?? I might even decide I don't want to go back to my home country and that I want to go somewhere else... say Australia... for God's sake what is wrong with that?? It's my choice, it is your choice where we all decide to stay at certain times of our lives (AS LONG AS WE DOING IT LEGALLY AND ARE NOT BREAKING THE LAW).
Totally agreed with you in this part!
CIC does not have any rules checking motives... unless you are a PR. and that is understandable because the the word says PERMANENT resident so you ought to be permanently here. However, if you meet obligations to be a citizen, CIC CAN NEVER and would NEVER deny you of getting your citizenship. It is the law and Canada is a country of laws. If you don't like the way the law is currently, then try to change it.
CIC does check a Canadian citizen who is residing exclusively outside Canada sponsoring a spouse, his/her intention to move back to Canada once the sponsored person get the PR visa. At the request of CIC, the Canadian citizen must provide proof of his/her intention such as job and housing arrangement.