But that would also be a completely different argument. Saying "swearing can be overplayed" is very different from suggesting that developers have to hold back because some kid might get their hands on the game. That should never be the game developer's responsibility, regardless of previous posts trying to use it as a smokescreen to justify removing foul language.
That aside, tolerances for flavor vary across the spectrum. Bioware games are relatively mild with their language. In keeping with your analogy, Pulp Fiction might be the equivalent of drowning your food with salt. But that also has its own huge appeal to certain fan groups, just judging by the film's overall popularity.
The Big Lebowski features the F word 260 times during its 117 minute run time, for a rate of 2.22 F-bombs per minute (keep in mind, there's no improvised dialogue on a Coen brothers film, so all of those "f--ks" were really in the script).
Anyways, how much swearing to have in the game seems like a bad thing to have decided in advance of writing the script. The most sensible strategy, it seems to me, is to simply write the dialogue that is most natural for the characters and the setting, and then let the chips fall where they may as far as how much bad language ends up in the game. Or you could just replace all of the foul language with Shakespearean insults like "You saucy boy!" Either one works for me. 