This was the most-common question that 750 owners would ask whenever they got together in numbers - with beer.
While I never heard Honda weigh in on it, some of my favorites were:
"It offsets the massive torque of the engine during acceleration."
"It helps keep your balance during the speed wobble when you're decelerating and let go of the handlebars" (this one is actually due to the offset front wheel...).
"It's because the alternator is in the way of my boot when I try to shift." (I think this one is pretty close?)
"It's because the oil tank on the right side is heavier than on the left, so this makes you shift your balance to match things up". (Huh?)
"Honda wasn't going to have a kickstarter at first, then decided later to have one, so the frame had to be modified." (Maybe?)