Back in the twenties, there was a movement, or let's call it a style called, "Power Archery". It was taught a lot in the schools and was fairly common in target archery until the late thirties and forties.
Basicly it was feet placed perpendicular, not sure about the spelling? Shoulders erect, bow vertical, placing the archer in a very bolt upright position. It was called Power Archery, and there were a few people who were very good at it. Like so many things in archery, not everything fits everybody.
Other coaches, and archers decided that a more natural way of shooting a bow might work better. While the vertical bow is still the perfered method in target circles, it does not hold a strangle hold over the way hunting archers shoot, at least not in the traditional arena.
I believe it natural to cant, in fact, if you ask any number of people to point at an object, they will use the index finger and rotate the hand slightly left or right depending if they are left or right handed. Most common is left rotation for the right hand, and right rotation for the left.
Couple this with the tendency to want to see the object we are shooting at as unobstructed as possible and you can see why you might like the cant.
I have had hunting shots where I could not cant, and had to shoot a vertical bow, I practice this so I can(at very close ranges)but the way I hunt, most often it is the other way around, I can't shoot with a vertical.
It really just comes down to what you feel more comfortable with. The short time I mess around with a gap, I used the vertical bow. When I gravitated to an instinctive style of shooting, I went to the canted bow, and have been there since.