If you are faced with the requirement to defend against bears, problems of access, portability, and storage make handguns the preferred method.
Defending is a different set of problems than hunting.
People get tired of carrying a long gun around the time, and keeping it in a constant state of readiness, when nothing happens for days, months, years.
Those are problems modern handguns and holsters have been perfected to solve, over a century and a half.
At my age, I wonder if I would nerves enough to draw, aim and accurately fire my Smith & Wesson .500 mag at a 500lb animal who was charging at me determined to kill me or at least cause me great bodily harm. Like I said, something I think about, but don’t really concern myself with ‘cause there ain’t too many bears out here in central Kansas.