I think this would be a great way to encourage players to follow a similar model where the charismatic, smart PCs fill more planner/leader roles with more combat oriented characters being their muscle. I think setting a good example is an ideal first move!
Then... Start making it so that a PC lacking the INT and CHA needed to be a real inspiration can NOT gain the higher ranks in groups all over the game. Sorry. Progress is barred you meathead! Go smash what I tell you to like a good boy!
This might sound scary at first but it's honestly not as damaging as it might seem initially. It's actually very possible to build a character that is pretty smart and charismatic but still very effective in combat. And if you choose to not invest in INT/CHA, that's okay too. You'll have a slight edge in a fight but you are choosing to accept that you will never be the big boss of anything for long.
Just a though!