In my opinion, no, cantilevers are not necessary. I prefer them because they allow easier fit for fenders and wider tires but not necessary. I have a couple of different bikes that would be considered touring bikes that do not have cantilever studs. I believe that they do have a little bit more mechanical advantage than side pull or center pull brakes but there are other things to consider. I'm a 230 lb clydesdale, so additional braking power is something I like. Lighter riders obviously don't have to worry about this as much as a porky old man like me.