Well, I've indicated before that I think if you're going to have both physical and mental attributes, they should both be similarly binding. The big part of the problem is broader I think; people can be really soggy about mental attributes having associated mechanics at all outside of a very narrow range.
I've been thinking about this thing about mental stats, and how I've frequently seen arguments along the lines of "it's especially important to enforce roleplaying around mental stats because those are the ones players want to ignore."
Except...
We ALL know that guy who thinks he's Mr. Smooth, and yet he rubs everybody the wrong way.
We ALL know that guy who is dumber than a sackful of hammers, but still pontificates about any and all topics.
We ALL know that guy who makes terrible life decisions, but tries to give everybody else advice.
And the crazy thing is they NEVER SEEM TO NOTICE. I mean, I'm still completely shocked when somebody blocks me on Enworld. It must be some kind of bug in the code.
(As the old saying goes: "Stupidity is like death. You don't notice when you have it; it's only the people around you who suffer.")
It's hard to kid yourself about your physical abilities, but people delude themselves about their mental abilities all the time.
So doesn't it make sense that characters with low mental attributes would be roleplayed as if they didn't?
What keeps them in line are the mechanics.
Player: "I'm going to go and put my patented moves on that cute barmaid."
GM: "Sigh. Ok, let's have a roll."
Player: "Let's see...uh-oh. Eight."
GM: "Yeah, she rolls her eyes and walks away."
Player: "She must not like the strong, handsome, successful adventurer type. Either that or she's being mind-controlled. Yeah that must be it."