I am still torn about this.  I am not a statistician, although I needed to employ a statistical rigor for my grad work.

There are several problems with surveys and modern cenus'.  The first key goal is random sampling.  It is very hard to achieve perfect random sampling.  The mandatory long form attempted this through coercion.  Answer it or you could go to jail.  The fact that no one did go to jail is not the issue.   The issue is coercion itself.  Every 5th house was to under threat of  jail or fines capitulate and fill the form.

I understand why it was done.  Firstly, because the threat got it done.  Very few people in the sample did not return a completed census form.  The idea is to achieve a ubiquitous distribution of data in the sample, and there-by understand trends.

The problem is that there is an assumption at some level that the data received is accurate and true.  This is an important assumption, but the intellectuals among us must admit the assumption or they cave in to intellectual dishonesty.

The classic example is the question about religious affiliation.  21, 000 people said "Jedi Knight"  The purely "random sample" in itself problematic, because there is a level of resentment toward the census for what is perceived to be an intrusion of the state.  Some, understand that the answers they give have a significant impact on their lives a year, or two from the moment they answer a question.
Some resent what they perceive to be an intrusion of the state.  Perhaps realizing the information may impact how foreign corporations and governments view Canada.  Some don't want to capitulate and give information to countries who consider us their enemies.

I am sure we could go on at length.  Purity is a myth.
For what ever reason Canadians are not cooperating even under threat of jail.  It is said of torture victims, they will tell the inquisitor anything they want to hear.  But the truth?  That is another matter.

Does that mean this is the right way to go?  I don't know.  I suppose, being somewhat of a contrarian, I like to ask and think about the the opposing view.  I also have this kind of resistance to what ever power structure I view to be coercive.  So being undecided, bring the long form back or don't it doesn't matter.  If people resent the intrusiveness enough, Jedi Knights are looking...