Hmm, I've never had a sorc, bard or Pali use it as a dump stat.
That's the irony; Charisma is a dump stat unless it isn't.
The problem has always been; if you were playing a class that didn't need a specific ability score, what does each score grant you?
Str: melee hit, damage, carrying, climb/athletics, feats of str (bending bars, opening doors)
Dex: AC, Reflex, Missile AC, stealth/thief skills, Init, avoid-falling-on-your-ass checks
Con: HP. Fort. More HP. Endurance/stamina checks. Did I mention HP?
Int: Knowledge Skills, Skill Points, Languages
Wis: Perception and Willpower
Cha: Social Skills
Lots of PC types don't need social skills: burly fighters, crude barbarians, brooding mages, silent rangers. As long as you have someone on the group who can handle diplomacy (such as a cleric, paladin or bard) you yourself rarely need to make checks. And since D&D is a team sport, the likelihood of being forced to parley with the king with only your 6 cha is fairly low (though not impossible).
Whereas you can't rely on the rogue's high dex to aid YOUR AC. Or the cleric's high wisdom to aid YOUR will save. They can, however, talk to the king on YOUR behalf.