Good questions.
First, ball pythons are tropical snakes. DO NOT brumate a ball python. Trying to brumate a ball python like a temperate zone snake is likely to kill the python.
A corn snake CAN be brumated but does not NEED to be brumated. Not even to induce breeding. Other species, like northerly species of garters, are brumated because it is part of the stimuli required to induce mating and reproduction. Even these do not NEED to be brumated if reproduction is not planned.
Sometimes, temperate zone snakes pick up stimuli that tell them it is time to brumate. Part of the preparation for brumation is to stop feeding and let the gut empty out. But nonfeeding snakes still use their body fat reserves for life support. Chilling them down for a couple of months minimizes the drain on their fat reserves. When they are warmed up, they are usually fine eaters. So in these cases, brumation is less stressful on both the snake and the herper than keeping the snake warm. But even in these cases, burmation is recommended rather than mandatory.
Paul Hollander