As much as I'd love to have a carrier (or helicopter assault ship), Canada does not really need one these days. We have very little need for power projection forces. That's why we don't have long-range bombers and/or a Marine Corps, like many other large nations (like USA, UK, France, Italy, Russia, China).
We don't have former colonies to help out, we don't have to attack enemies at long distances, and we already can control the sea apporaches to our nation (although US support far extends our range in this regard). Yes, a carrier (big or small) would have helped us dole out humanitarian aid after the 2004 tsunami or Hurricane Katrina, but that shouldn't be the reason we are buying them.
Personally, if the military wants something like this, I say stretch the
Joint Support Ship they want to build and let them operate a half a dozen choppers (the current plans allow for a deck capable of two choppers). We get the best of both worlds that way. The only problem is that the JSS is already over-burdened with roles and this might add too much...