Charisma as a stat.... Do we really need it?
Climbing in the WABAC machine with Mister Peabody and Sherman and checking things out, charisma has been a mostly ignored stat from day one and yet always there. Its kind of like laws for lawmakers. It gets lip service but never really used.
Sure back in the day if you weren't a shining example of beauty and poise and presence you couldn't be a paladin. (17 Charisma requirement when 18 was the highest you could have for those who don't have a WABAC machine.)
It was used in following game systems, primarily due to inertia really I think. 'DND has it and players need a number to dictate how good looking they are don't they?'
And yes I do I know, charisma isn't just about looks but that's how every player I've ever met treated it, not how much presence or leadership or whatever they had. It was always, woohoo a 17 charisma, I look maaaahvolus. And the inverse a 5 charisma, damn I'm Ernest Borgnine (who is a wonderfully charismatic individual)
It was the ultimate in dump stats since it just really never mattered in any situation mechanical or narration barring the one class that it was a requirement to have for some reason.
Then WotC made the sorcerer in 3.0 that got to base their power off their presence. So now it was mostly ignored for only most of the classes.
A good GM would somehow work in narrative elements for extreme charisma both good and bad but in general the vast spread of the bell curve was meaningless. "The orc tribes find your ugliness attractive and welcome you into the village."
As a result for me, charisma has gone the way of the dodo bird, or more correct perhaps, the way of the appendix. It's an unnecessary organ in the body of an RPG system.
In my system, a character's physical appearance is exactly what the player says it is. There are situational pros and cons to being ugly, average and good looking and they tend to balance out to me. The non-physical portion of the gestalt charisma effect is determined by their skills and lack there-of. A person with a high empathy or social skill in a social situation? Pretty charismatic. A person with a high martial ability in a war situation? Pretty charismatic.
Someone who's netting a -10 penalty because they don't have any such skills? Pretty non-charismatic.
The mechanical portion though, for me, makes up only a portion for the average player, the rest is what the player has the character say, how they make them act and react and in general how they narrate their character. Sure if a player has no desire to, or confidence in their ability to 'role play', i.e. the player who sits there mumbling "When do we get to roll dice and kill things?" then the mechanics are the whole ball of wax. But in general most players can be engaged to some extent in non-dice rolling with a little encouragement and most importantly, some reward for doing so.
FYI, Players are like rats in a maze. If you don't reward them with some cheese for reaching the center, they stop trying.
Anyway, so if you're designing a game system, ask yourself if you really need a mechanical number to dictate how much charisma a player's character has and if it wouldn't be better to encourage them to be as charismatic as they want their character to be through actual dialogue and actions.
Who knows we might subtly influence the leanings of today's societal behaviour as a result. In a good way that is.