I guess my immediate answer is that pigeon-holing the player character to be the charismatic party leader mechanically restrains our choice of classes to Bard, Paladin, Warlock, or Sorcerer.
True.
As to "breaking" other Classes - let us not exagerrate. 12 CHA plus plus lavish use of Inspiration Points (of which there is Million), and an Absolute Brand will get you through many dialogues.
Also, an example being e.g. Githyanki Patrol - IIRC none of the tests is CHA based, but INT or WIS. Even if there is a CHA test, it is one of several, hence a charasmatic halfwit can easilt blow it and lead to battle.
Also - Eagle's Splendor (you do have a Cleric in the Party, don't you?).
I admit that CHA 16 and Proficiencies in Persuasion/Deception and/or Intimitation make the game MUCH easier. I play Bard hybrids for a reason :P
BTW - as "advertised" by Larian, "TAV always the speaker" works "most of the time". I just had Shadowheart stammering through a dialogue with some Friendly Duergar TM :P
"Always TAV" and "always nearest partymember" - neither is perfect, switching does not always work, and I'm leaning to "nearest PC" as the Lesser Evil.
The one time I really, REALLY was happy with "Always TAV" was the Hag fight - I did not have to do crazy character positioning to have the Face be nearest to her when she was at 10HP.
I know that I am rpeating myself to large degree
