LOL, I'm an old guy and I really liked, cantilever brakes that I had on a few of my old bikes. What makes the "V-Brake" so much better that it replaced the cantilever brake?? I could adjust the cantilever brakes easily but it seems a real chore to adjust the V-brakes.

It comes from mountainbiking and I think the main reason is to allow for huge tires to pass through them when opened.
They also allow for more clearance between brake housing and wheel so to eat less dirt.
They aren't real easy to set up like cantilevers but once you get the hang of 'em it's actually not that hard.
Roadracebikes still have canti's but most hybrids use mountainbike gearing and brakes.

Everything that you said is true. I'd just like to say that road bikes have caliper brakes and cyclocross have cantilever... Not a big detail. But anyway, I'm pretty sure they are used because they have a higher mechanical advantage, which equals more stopping power.

V-brakes (a.k.a. side-pull cantilever) are cantilever brakes.
They were developed for mtbs, for two main reasons: power (the mechanical advantage of the longer arms/cable pull) and the need for a brake to work well with suspension.
Traditional cantis rely on (centred) cable stops mounted somewhere on the frame; these don't play well with the movement of suspension (front and/or rear), or with the sometimes complex cable routing required for rear suspension. Solution: develop a brake that does away with the centred cable stops.
Once discs became mainstream, v-brakes began to disappear from mtbs, but have remained common on hybrids and touring bikes (power, relative to traditional cantis).

V-Brakes are the most powerful non disc brake. Canti's have more mud clearance but dont stop as well and are more finiky to set up than V-Brakes, why CX bikes persist in using canti's illudes me now but they do look good.

The race I went to on the weekend, the cool cats had discs. Times are changing rapidly here in Japan's cyclocross scene.

Can't imagine why ? (LOL) : )

Cantilevers allow adjustment of mechanical advantage by lengthening or shortening the cable. On V-brakes, that mechanical is fixed by the length of the arm.

A well adjusted cantilever will stop you as well as the same well adjusted V brake... but for most a cantilever is harder to set up and for some is like magic while setting up a V brake is rather simple and I have a tutorial I use in classes that turns what seems like a hard job into one that is ridiculously easy.

Getting a high quality cantilever will cost more than a lesser V brake that will stop you just as well so in many cases, price comes into play and if you are running wider fenders you may find that the standard V brake interferes and that a model designed to work with wider fenders (they have more arched arms) will be needed.