Some companies tend to view HR as a non-essential function and rather than partner with HR they tend to see it as an "oppressive" force as indicated in this article.
From my point of view, as a working HR manager (in the US), HR is as much risk management as anything else given the enormous amount of compliance that has crept into employment. Perhaps it is different in Canada. Having been in HR for 20 years I have seen it change, but many companies still don't really understand what it does. Divvying the HR function up and including it with other positions is typically a bad idea. Often times there are crucial steps not addressed due to the lack of education of the person who inherits the jobs in the HR field; it then reverts back to an administrative role that doesn't help the company to attract, retain, train and promote employees.
Why wait until employees leave to ask them questions about their overall job satisfaction? Anonymous surveys given at least annually should give you a pretty good idea of who is going to stay and who is going to leave and why.