The police don't just carry guns. They carry pepper spray and a baton. They understand (and are trained) that different situations require different measures of force. So should everyone who carries a gun.
Having a gun as your ONLY defensive weapon increases the likelihood it may be used in a situation where a non-lethal weapon would be a better choice. For this reason, I also carry Fox Labs pepper spray in a quick-draw holster. I get the narrow stream nozzle, for longer distance and better performance in wind. However, it's harder to hit your target with it. Pepper spray PRACTICE is also necessary. You don't carry a gun without practicing with it. The same logic should apply to pepper spray.