Well I think you put your finger on it, no body wants to get shot, even a little bit. With the state of medicine of that era a .22 was about as deadly as a .44, it just took a week longer to get there. They were carried more for a threat than for a shootout.
But today there are much better choices available. Consider that one is legally justified in shooting only if the opponent represents an imminent threat, such as weapon in hand. Do you really want to shoot them with something that for sure will not put an instant end to the threat? Personally I'd go for more power.
Then there is the reliability issue. I very rarely have a misfire with C&B revolvers that I have tuned up and loaded but I have never found a 100% solution to spent cap jams. What may be only an inconvenience on the range can get you killed in a fight. Power is good, accuracy is nice, but 100% reliability is paramount in a defensive weapon and I've never found that with cap&ball revolvers.
If I faced an altercation when I happened to be carrying a C&B revolver I would not feel unarmed, but if I expected trouble I would for sure be carrying a modern firearm.