I'm going to give you an answer to why Americans swear so much at least now in public but also in private as well that is a lot less scientific than what Olga Khazan gives you. But before that I'm just to go on the record and say I'm not a religious fundamentalist or very religious at all and don't even practice any religion and I'm not a prude. Of course I swear like most Americans do I just have a real purpose to it and don't feel the need to sound cool and lot of times today swearing is generally used simply to sound cool and hip. People will swear really for no other reasons other than that.
I swear to express anger and amazement and no other reasons. "Holy shit! That man is fat!" Would be an example of someone showing amazement and being caught off guard. "Why don't you watch where the fuck you're going, are you trying to fuckin kill me?" Would be an example of someone expressing anger because they think someone is moving too fast generally in a vehicle and moving recklessly. But most Americans swear today and cable TV especially HBO and company is a perfect example of that because that is simply their normal vehicle of communication. That is how they talk to their friends, that is how their friends talk and it seems perfectly normal to them. That is how cool people talk today.
If you want to sound cool today you swear a lot and even do it for no apparent reason. "Where the fuck is he? He was supposed to be here 2 minutes ago. Fuckin lazy ass!" Now was that really called for or could that person just so a little patience instead and say, "relax, he'll be here." Or not even say that and just enjoy that time waiting a few minutes. Maybe get a latte and stare at their iPhone and pretend to look hip and important for a few minutes.
The more you swear and sound cool doing it, the cooler you'll be in American pop culture. And if you're in entertainment the more you swear the more popular you'll be and the more roles you'll have in movies or on HBO or the other networks where hard-core swearing is not just allowed but encouraged. The bigger the asshole you are the more attention you'll bring to yourself as the reality genre as proven the last fifteen years or so. You don't have to do a scientific study to prove this but simply be aware of your own surroundings and what is going on in culture today.
The fact that we now see more cussing in American politics today whether its lets say moderate cussing with the use of the word damn and hell, screw, and other words like that not just on cable news, but network news where you would think the people there would be more moderate and cognitive with their approach to how they express themselves, is just an example of how pop culture hasn't just infiltrated our political system, but that our political system is a reflection of our pop culture in America.
And saying what the heck, or darn it all, gee wiz, just sounds too 1950s Leave it to Beaver for most Americans today. Especially when you can say I don't give a damn or what the hell, that is a helluva a lot, and not pay any price for it. You don't need to poll people or do any scientific research on this and ask people why they swear regardless of their profession. You just have to be aware of what's going on in front of you and see it for yourself.
The Atlantic: Opinion- Olga Khazan: Does Swearing Make You Likable?