Deflation in a service based economy is nothing less than a hammer blow.
If prices are low, or are getting lower, why buy now when you can get it cheaper in a month? People quit spending. Service based industries lay off staff. Layoffs lead to less spending. Less spending leads to more layoffs.
Suddenly you have a economy heading strongly in the wrong direction and the BOC would need to cut rates dramatically to increase consumer spending.
Sure, people can get goods and services for cheap for a while, but it's going to cost them their jobs