Submarines are of course a valuable part of naval warfare, and a requirement for a serious Navy. And, no one can doubt the proffessionalism and dedication of the sailors who man them.
However....
We have three submarines, which at some point, someone made the decision to purchase. At some point, someone in the military also decided that we did NOT need: tanks, troop-transporting helicopters, serious air-air refuelling, strategic air or sea lift, an Airborne regiment or elite/QRF light Inf capability, etc.
I fail to see why we need submarines more than we need tanks, or Chinooks, or possibly a decent ammo budget for the year, or maybe enough kit to equip a uni going to Haiti.
Do we need subs to exercise sovereignty over our waters? No, surface ships can do that. Do we need sub's to monitor our territorial waters for fishing and smuggling? Aurora's and frigate and CPF's can do that. Do we need subs to protect our coastline or shipping routes from enemies? No, we have the USN for that. Do we need subs to fight a major naval conflict? If we're building a Navy to fight a major blue-water engagement, I think we're spending in the wrong place.
Granted, subs could make an important contribution to any of the above missions - but are they necessary? The issue is not if subs are important, the issue is are subs MORE important then any number of other capabilities that could also use a $750million infusion?
The decision to purchase subs, to me, represents an ad hoc system of capabilities and major systems purchasing that is indicative of Canada's lack of a serious up-to-date defence policy. If Ottawa had a thought out, long term policy that stated the primacy of the Navy and a priority for coastal defence, and a limited, peacekeeping/boyscout role for the army, and an air force dedicated to shooting down errant airliners, I could be happier. In the end, someone decided that submarines are a more important weapon systems to Canada's national security for the next 25 years than troop transporting helicopters or MBT's. We have a limited defence budget, and we can't have all the gear and equipment we want, and in reality where we have to pick and choose which capabilities we want to invest in. Whether submarines were the right capability to place limited funds into is debatable.