Nothing wrong with that. If you played an Int 6 character and started making genius-level observations about an elaborate plan to decoy the orcs with a series of co-ordinated feints, and your DM said that you were roleplaying badly, would you complain? The problem is a lot of advanced roleplayers slap a low score in Charisma and then completely disregard it from a roleplaying point of view. Since Charisma is the roleplaying stat, to not roleplay it is to ignore it. Claiming that your DM overruling your depiction of Charisma is no more 'cramping your style' than saying because you have Strength 4 you can't lift a horse is.
Two things:
1) There's a bit of a double standard with regards to what mental abilities receive such "you can't do that" attention, and whether they do because they're high and low, though. For example, I've
never had a character stopped from doing something for having low WIS, nor ever seen anybody else have the same done to them - it's all been self imposed if it manifested at all. Likewise, few DMs seem to stop the game and say, "You can't do that, your INT is too high to do something that dumb" when the 18 INT PC's player does or says something stupid. As mentioned above, CHA gets special attention, because people want it to matter in particular, and I argue that sometimes that gets taken too far.
2) Comparing it to STR is apples and oranges - STR is
easy to map to the game because it's applications are usually numerically quantifiable, and it doesn't directly affect roleplaying choices regarding the personality of your character - unless you're concerned with whether your character is a beefcake or not, and make that matter to the personality. You paint it as I want to have my cake and eat it - well, I think that it's more about annoyance that the game effectively punishes some roleplayers for playing a certain personality of character by lessening their more combat-related ability scores, effectively balancing combat penalties with roleplaying bonuses (and CHA, except for the odd skill like Bluff, or if you're a sorceror, doesn't go far in this respect). This is deemed bad game design elsewhere in 3E. I can envision a version of the system without quantification of any mental abilities, and no social skills - in other words, one that lets the players get on with the roleplaying, and leave the numbers to in-game physical tasks such as combat, casting spells, or sneaking. It's a minor gripe, but it is a weakness that I can see with the system nonetheless.
On a related note, I remember reading in a post by a designer on Monte Cook's boards that the social abilities are merely there to speed up the game when time consuming 1 on 1 player and DM interaction is going on (such as when attempting to gather information) so that the other players don't get bored. If this is the only reason they exist, apart from boosting the usefulness of CHA, I think that they can safely be disposed of under a variant D&D which is lacking in mentally mapped ability scores.