By coincidence, when I returned from the genealogy meet-up on Thursday where a lot of the conversation was about newspapers I found LAC had posted on their blog an item "Why Consult Newspapers on Microfilm?"
The answer to the question posed is no mystery, although you won't read it in their blog post. LAC has been so backward in pursuing newspaper digitization, as has been done by all their major peer national libraries, that Canadians have no choice but to use microfilm technology from the 1930s. LAC don't explain why in their blog post, or anywhere else. That's even though LAC managers are well aware that this is a major irritant for the genealogical and historical communities with LAC's performance.
For an update on newspaper digitization I commend to LAC management International Preservation News from IFLA the May issue of which is dedicated to Digitization and Preservation of Newspaper Collections. Download as a pdf at http://www.ifla.org/files/pac/ipn/IPN%2056.indd.def.pdf
On a broader theme, there's an International Conference “The Memory of the World in the Digital Age: Digitization and Preservation”, 26-28 September 2012, in Vancouver where there is no participant from LAC among a large international contingent of speakers,