I say ease up a little -- good arguments for that in this thread -- but stick to your guns that Charisma (and roleplay skills) should be important.
I had a similar problem with the campaign I'm currently running --
all my characters used Charisma as a dump stat. The monk has an 18 Int (smart of the player) and is using his oodles of skill points to make up for it, but it's still hurting the party.
At the start of the game, I debated for a while how I was going to deal with that -- add some important r-p encounters and require checks, or what? Once the game started going, though, it kind of resolved itself: A lot of times came up when it seemed natural to ask for diplomacy/bluff/whatever checks (A note: I highly recommend incorporating these things, even letting them override how well the players actually role-play. After all, if a player skillfully stabbed me in the face, I wouldn't treat that as a critical hit against one of my NPCs...)
Of course, typically these situations are just resolved by whatever character is best at social interaction. Every once in a while, for whatever reasons (a combination of their choices and the state of things in the world), the poor-Cha players will end up having to make those checks on their own -- at which point, they'll regret the dump. (My players are normally good about not playing the "but the book says!" card, but when I allowed the Pantomime skill from the Kalamar Player's Guide, but switched the key ability to Cha -- you know, so it actually makes sense -- it raised a pretty big argument, which pretty much boiled down to "but I have a 14 Wis and only a 7 Cha!")
Curiously, I've found that these checks, while less common than others, can be some of the most important ones. The course of an entire campaign can be change by a fumbled Diplomacy roll -- and a decent Bluff can be the difference between getting some good information and getting a poisoned dagger between the ribs. That latter part was as close as any of my PCs have ever come to dying this campaign -- the group had split up to gather information, feeling safe in town, and the dwarf aroused some suspicions in the wrong person. In combat, he would have had someone right there to heal him -- instead, he had to stumble through town looking for his allies, as his Constitution slowly ticked away.
Did I set up the situation like that to punish him? Not at all. It was just the most appropriate form of resolution provided by the rules. The dwarf actually got
bonus XP for that, because (aside from just the checks) he also role-played his character's carelessness and stupidity

Not something I'd ever force or coax players into doing, but something that deserves a nod nonetheless.
So, in short, I'd say that simply penalizing the equipment really isn't the answer -- just employ the ruleset in a manner which makes sense. If social interaction is important in your game, the rules will express that Cha penalty appropriately -- if social interaction isn't important in your game, then there's nothing to penalize.