I've never seen CHA as a throw away stat myself :)
While I agree with the OPs points in general, I think they apply to just about all games (certainly all the one's I've played in) and not just limited to Kingmaker.
Regarding the "good kingmakers" - these really only have to apply to the party in general. You can certainly get away with only one CHA-based characters who does the bulk of social interactions and most likely becomes the ruler.
When I started running Kingmaker, almost all my players fit the bill for what you describe as "good kingmakers" with a minimum of 12 CHA for every character and they got slaughtered. Now the party has two people with CHA penalties and even the bard only has a 13. They're doing much better now.
The best and easily most admirable character in our campaign is our fighter and general, Marcus Muri. My cleric has kept this meat shield alive since day 1, when he decided to "negotiate" with the bandits at Oleg's, and was promptly surrounded and attacked by them. He's... incredibly simple, and even though NG at least follows Gorum on his sheet, but... his overall goal is to become the defender of a farming community with his pretty, stacked, but ignorant ranger gal toy and son. Suffice to say charisma is not his strong suit, at least stat-wise, and he has NO interest in politics, but the people love him. My cleric has pulled out the stops to promote him above all others, including the redeemed paladin of Sarenrae Akiros Ismort as a champion of our nation, including commissioning action figures in his likeness for children to play with. In return, he's made slurred, drunken advances on her when she was playing midwife to his girlfriend, and she's godmother to his son.
All the rest of us, save the darn ruler, have some manner of personal ambition which keeps us segregated from other members of the party, and making ruling phases kinda difficult. RP opportunities with other nations at table are kind of a chore.
*shrug* i guess you have to design your party around a pre determined leader character. in our campaign, the day we were _supposed_ to vote as to who would lead it should have been a toss up between my cleric and the cavalier, but I quickly found my character put down simply because she was religious, and the remainder of the group had agreed previously that because the cavalier had made charisma his primary stat, it was obvious that he should be ruler. didn't even matter what he played in game, just OOC, definitely it should be his job...
* Players who hate to deal with NPCs - Dealing with NPCs in a diplomatic fashion is important.
THIS, oh God this. My players never interact with NPCs beyond what I throw in front of them (IE, if they need to go buy something from Oleg, they'll interact with Oleg because I have Oleg come out and talk to them; if Brother Kavken needs them for a mission, Brother Kavken will come out and talk to them and hand them the mission, but afterward they'll never approach him until the mission is done.)
It's pretty annoying, honestly, and I really should have thought of this prior to my starting the game up. (Though when I did start the game, I had a much larger group with two really good, sociable PCs who do chat up members outside of the party. They have unfortunately left - one due to scheduling conflicts, the other because the group was too large for him.) And it's caused a lot of problems for them when they're trying to figure out which NPCs to recruit to help fill their leadership roles.
(And of course, I can already foresee the king having difficulty down the line in that if he continues RPing an insular, isolated guy, he's never going to find himself a wife, which he's already expressed some interest in doing.)
You can ever boil down further to a single question: do your players and you enjoy RP? If yes, then Kingmaker is for you. If no, and hack-n-slash is their way, then Kingmaker probably isn't for you.
This AP takes a certain type of mindset IF you want to run the actual kingdom building.
IMO, if as a DM you want to run this AP and hesitate because of your players, there are some great resources on resolving problems before they occur. One of the wonderful things about PF's DMG is the section on (problem) player archtypes and dealing with them. Second, there are some good threads on these message boards discussing setting things up.
I want to DM this AP. I want to play this AP. Regardless of which happens first, I will probably bully the players into a single session of doing nothing but setting up the group, goals, etc. In other words, none of this we all happen to be in the same pub business. The players have to be in the right mindset from the getgo to extract the full joy from this. So do DMs.
While I agree with the OPs points in general, I think they apply to just about all games (certainly all the one's I've played in) and not just limited to Kingmaker.
Regarding the "good kingmakers" - these really only have to apply to the party in general. You can certainly get away with only one CHA-based characters who does the bulk of social interactions and most likely becomes the ruler.
When I started running Kingmaker, almost all my players fit the bill for what you describe as "good kingmakers" with a minimum of 12 CHA for every character and they got slaughtered. Now the party has two people with CHA penalties and even the bard only has a 13. They're doing much better now.
I agree with Tem's first point. These types of characters can be a problem in just about any kind of game (unless everybody at the table plays the same way and enjoys it), and thtat problem is just accentuated in Kingmaker.
As to his second point, I disagree to an extent, unless those PCs with negative Charisma modifiers are not taking leadership roles in the kingdom. If they are, their image will effect how the whole kingdom is viewed. Kind of like how a President's popularity can be effected by the public perceptions of the people in his Cabinet. Of course, I am also notorious for making everybody use every stat on their sheet occasionally. The "face" can't be everywhere, all the time, and some people aren't going to want to deal with just him. That would be kind of like insisting everyone who wanted to talk to you in real life talk to your lawyer instead. Neither practical nor effective.