I am being nothing less than honest. I am not Joe Schmoe in real life. If my character has a 10 int, I have to play him like he is almost a moron. A 10 charisma means he is either unremarkable(in other words, he says nothing catchy and draws little attention, or, that half of the attention he attracts is unsavory. He is certainly not going to be likable and gregarious, now, is he) a 10 wisdom means you're no wiser than the village blacksmith. It limits the roles you fit into. A 16 charisma means you can be smart, funny, and witty, and sometimes rude, and get away with it, or, beautiful, and charming and sagacious. Either one. Or even slick, and manipulative. A 10 charisma character can be beautiful but a social moron, or smart and rude, or manipulative but unsuccessful, or just plain unremarkable nothing.
The roles the 10 gets to engage in are remarkably unfun to me, and thus, charisma is never my dump stat.(Unless the dm makes the characters and sticks me with the half-orc barbarian...*sigh*)
Physical stats arent nearly so important in defining personality, but I dont see where you get this "Over-acting dinner theatre" idea. Roleplaying is about playing a role. John, the idiot drooling son of the blacksmith, with a powerful physique, isnt exactly the role I am gunning for.