I've followed the logic through with Ollydbg and it seems that originally they used to have a menu option for toggling intro movies on/off in the Options menu but they took it out. Instead they are hardcoding the instruction to toggle it on by default. And, I believe the reason there is no INI file/command-line/dev console option for toggling it is that they didn't provide one. The "UI/Disable Intro" string is just the title of the option for display in the Options menu and the longer string is the description. You'll notice that it is the only command in the entire strings table that lacks a command associated with it. They might add this in a future update if enough customers are angry about it, however. Perhaps we should petition them to do this.
On an unrelated note, someone out there might find these useful. I found them while looking for a way to solve the intro problem.