Calipers are not a wear item - though rarely the seals or boots need replacing - so I see no reason to replace one unless it fails. A sticking caliper can result from dust boot failure, or contaminated or deteriorated brake fluid. It is important to determine the exact cause and type of failure making it stick to evaluate then extent of further damage to the braking system.
In our Honda Accord I discovered a bent slide-bolt for one of the front calipers. That caused both 'sticking' behavior and ineffective braking at that wheel. The caliper was fine - with a new bolt installed. The disk on that side was burned - strange pattern. Apparently the damage had occured during a prior shop job, and would not have been apparent if a simple pad replacement was being done.